diff --git a/lib/validation/dispatchervalidation.inc.php b/lib/validation/dispatchervalidation.inc.php
index 40422e5..5e539be 100644
--- a/lib/validation/dispatchervalidation.inc.php
+++ b/lib/validation/dispatchervalidation.inc.php
@@ -225,6 +225,26 @@ class KTDispatcherValidation {
         return $sString;
     }
 
+    function validateIllegalCharacters($sString, $aOptions = null) {
+        $sString = trim($sString);
+        if (empty($sString)) {
+            $aOptions['message'] = KTUtil::arrayGet($aOptions,
+                    'message', _kt("An empty string was given"));
+            $this->handleError($aOptions);
+        }
+        
+        // illegal characters: /\ <>|%+':"?* 
+        $pattern = "[\*|\%|\\\|\/|\<|\>|\+|\:|\?|\||\'|\"]";
+        if(preg_match($pattern, $sString)){
+            $sChars =  "\/<>|%+*':\"?";
+            $sMessage = sprintf(_kt('The value you have entered is invalid. The following characters are not allowed: %s'), $sChars);
+            $aOptions['message'] = KTUtil::arrayGet($aOptions, 'illegal_character_message', $sMessage);
+	        $this->handleError($aOptions);
+        }
+
+        return $sString;
+    }
+
     // validate a STRING to an integer
     function validateInteger($sInteger, $aOptions = null) {
         $sInteger = trim($sInteger);
diff --git a/plugins/ktcore/KTCorePlugin.php b/plugins/ktcore/KTCorePlugin.php
index 24bc338..5a9b5bc 100644
--- a/plugins/ktcore/KTCorePlugin.php
+++ b/plugins/ktcore/KTCorePlugin.php
@@ -174,6 +174,7 @@ class KTCorePlugin extends KTPlugin {
 
         // validators
         $this->registerValidator('KTStringValidator', 'ktcore.validators.string', 'KTValidators.php');
+        $this->registerValidator('KTIllegalCharValidator', 'ktcore.validators.illegal_char', 'KTValidators.php');
         $this->registerValidator('KTEntityValidator', 'ktcore.validators.entity', 'KTValidators.php');
         $this->registerValidator('KTRequiredValidator', 'ktcore.validators.required', 'KTValidators.php');
         $this->registerValidator('KTEmailValidator', 'ktcore.validators.emailaddress', 'KTValidators.php');
@@ -183,6 +184,7 @@ class KTCorePlugin extends KTPlugin {
         $this->registerValidator('KTFieldsetValidator', 'ktcore.validators.fieldset', 'KTValidators.php');
         $this->registerValidator('KTFileValidator', 'ktcore.validators.file', 'KTValidators.php');
         $this->registerValidator('KTRequiredFileValidator', 'ktcore.validators.requiredfile', 'KTValidators.php');
+        $this->registerValidator('KTFileIllegalCharValidator', 'ktcore.validators.fileillegalchar', 'KTValidators.php');
         $this->registerValidator('KTArrayValidator', 'ktcore.validators.array', 'KTValidators.php');
 
         // criterion
diff --git a/plugins/ktcore/KTFolderActions.php b/plugins/ktcore/KTFolderActions.php
index 8c4e096..bb42722 100644
--- a/plugins/ktcore/KTFolderActions.php
+++ b/plugins/ktcore/KTFolderActions.php
@@ -96,7 +96,12 @@ class KTFolderAddFolderAction extends KTFolderAction {
         $oForm->setValidators(array(
             array('ktcore.validators.string', array(
                 'test' => 'name',
-                'output' => 'name')),
+                'output' => 'name',
+            )),
+            array('ktcore.validators.illegal_char', array(
+                'test' => 'name',
+                'output' => 'name',
+            )),
         ));
         
         return $oForm;
diff --git a/plugins/ktcore/KTValidators.php b/plugins/ktcore/KTValidators.php
index 5faccfb..de68cbb 100644
--- a/plugins/ktcore/KTValidators.php
+++ b/plugins/ktcore/KTValidators.php
@@ -89,6 +89,53 @@ class KTStringValidator extends KTValidator {
     }
 }
 
+class KTIllegalCharValidator extends KTValidator {
+    var $sNamespace = 'ktcore.validators.illegal_char';
+    var $sWarning;
+    
+    function configure($aOptions) {
+        $res = parent::configure($aOptions);
+        if (PEAR::isError($res)) {
+            return $res;
+        }
+        
+        $sChars =  "\/*<>|%+':\"?";
+        $sWarning = sprintf(_kt('The value you have entered is invalid. The following characters are not allowed: %s'), $sChars);
+        $this->sWarning = KTUtil::arrayGet($aOptions, 'illegal_character_warning', $sWarning);
+            
+        $this->bTrim = KTUtil::arrayGet($aOptions, 'trim', true, false);      
+    }
+    
+    function validate($data) {
+        $results = array();
+        $errors = array();
+        
+        // very simple if we're required and not present, fail
+        // otherwise, its ok.
+        $val = KTUtil::arrayGet($data, $this->sInputVariable);
+        
+        if ($this->bTrim) {
+            $val = trim($val);
+        }
+
+        // illegal characters: \/ *<>|%+':"?
+        $pattern = "[\*|\%|\\\|\/|\<|\>|\+|\:|\?|\||\'|\"]";
+        // "'^[^:]+:(?:[0-9a-z\.\?&-_=\+\/]+[\.]{1})*(?:[0-9a-z\.\?&-_=\+\/]+\.)[a-z]{2,3}.*$'i"
+        if(preg_match($pattern, $val)){
+            $errors[$this->sBasename] = $this->sWarning;
+        }
+
+        if ($this->bProduceOutput) {
+            $results[$this->sOutputVariable] = $val;
+        }
+        
+        return array(
+            'errors' => $errors,
+            'results' => $results,
+        );
+    }
+}
+
 class KTEntityValidator extends KTValidator {
     var $sNamespace = 'ktcore.validators.entity';
     
@@ -429,6 +476,52 @@ class KTFileValidator extends KTValidator {
     }
 }
 
+class KTFileIllegalCharValidator extends KTValidator {
+    var $sNamespace = 'ktcore.validators.fileillegalchar';
+    var $sWarning;
+    
+    function configure($aOptions) {
+        $res = parent::configure($aOptions);
+        if (PEAR::isError($res)) {
+            return $res;
+        }
+        
+        $sChars =  "\/*<>|%+':\"?";
+        $sWarning = sprintf(_kt('The name of the document selected is invalid. The following characters are not allowed: %s'), $sChars);
+        $this->sWarning = KTUtil::arrayGet($aOptions, 'file_illegal_character_warning', $sWarning);
+            
+        $this->bTrim = KTUtil::arrayGet($aOptions, 'trim', true, false);      
+    }
+    
+    function validate($data) {
+        $results = array();
+        $errors = array();
+        
+        $aFile = (array) KTUtil::arrayGet($data, $this->sInputVariable);
+        
+        // Get the file name
+        $val = $aFile['name'];
+        if ($this->bTrim) {
+            $val = trim($val);
+        }
+
+        // illegal characters: \/ *<>|%+':"?
+        $pattern = "[\*|\%|\\\|\/|\<|\>|\+|\:|\?|\||\'|\"]";
+        if(preg_match($pattern, $val)){
+            $errors[$this->sBasename] = $this->sWarning;
+        }
+
+        if ($this->bProduceOutput) {
+            $results[$this->sOutputVariable] = $aFile;
+        }
+        
+        return array(
+            'errors' => $errors,
+            'results' => $results,
+        );
+    }
+}
+
 
 class KTArrayValidator extends KTValidator {
     var $sNamespace = 'ktcore.validators.array';
diff --git a/plugins/ktcore/document/Rename.php b/plugins/ktcore/document/Rename.php
index 571382a..7c0ac13 100644
--- a/plugins/ktcore/document/Rename.php
+++ b/plugins/ktcore/document/Rename.php
@@ -77,7 +77,7 @@ class KTDocumentRenameAction extends KTDocumentAction {
         $fields = array();
 
         $fields[] = new KTStaticTextWidget(_kt('Current file name'), _kt('The current file name is shown below:'), 'oldfilename', $this->oDocument->getFileName(), $this->oPage, false);
-        $fields[] = new KTStringWidget(_kt('New file name'), _kt('The name to which the current file should be renamed.'), 'filename', "", $this->oPage, true);
+        $fields[] = new KTStringWidget(_kt('New file name'), _kt('The name to which the current file should be renamed.'), 'filename', $this->oDocument->getFileName(), $this->oPage, true);
 
         $oTemplate->setData(array(
             'context' => &$this,
@@ -95,6 +95,7 @@ class KTDocumentRenameAction extends KTDocumentAction {
             'max_str_len' => 255,
         );
         $this->oValidator->validateString($sFilename, $aOptions);
+        $this->oValidator->validateIllegalCharacters($sFilename, $aOptions);
         
         $res = KTDocumentUtil::rename($this->oDocument, $sFilename, $this->oUser);
         if (PEAR::isError($res)) {
diff --git a/plugins/ktcore/folder/Rename.php b/plugins/ktcore/folder/Rename.php
index 5806bb0..61dfc5f 100644
--- a/plugins/ktcore/folder/Rename.php
+++ b/plugins/ktcore/folder/Rename.php
@@ -55,7 +55,7 @@ class KTFolderRenameAction extends KTFolderAction {
         $oTemplate =& $this->oValidator->validateTemplate('ktcore/folder/rename');
 
         $fields = array();
-        $fields[] = new KTStringWidget(_kt('New folder name'), _kt('The name to which the current folder should be renamed.'), 'foldername', "", $this->oPage, true);
+        $fields[] = new KTStringWidget(_kt('New folder name'), _kt('The name to which the current folder should be renamed.'), 'foldername', $this->oFolder->getName(), $this->oPage, true);
         
         $oTemplate->setData(array(
             'context' => &$this,
@@ -72,6 +72,7 @@ class KTFolderRenameAction extends KTFolderAction {
         $sFolderName = KTUtil::arrayGet($_REQUEST, 'foldername');
         $aErrorOptions['defaultmessage'] = _kt("No folder name given");
         $sFolderName = $this->oValidator->validateString($sFolderName, $aErrorOptions);
+        $sFolderName = $this->oValidator->validateIllegalCharacters($sFolderName, $aErrorOptions);
         $sOldFolderName = $this->oFolder->getName();
 
         if ($this->oFolder->getId() != 1) {
diff --git a/plugins/ktcore/folder/addDocument.php b/plugins/ktcore/folder/addDocument.php
index 5c00889..60f99dc 100644
--- a/plugins/ktcore/folder/addDocument.php
+++ b/plugins/ktcore/folder/addDocument.php
@@ -132,10 +132,18 @@ class KTFolderAddDocumentAction extends KTFolderAction {
                 'test' => 'file',
                 'output' => 'file',
             )),
+            array('ktcore.validators.fileillegalchar', array(
+                'test' => 'file',
+                'output' => 'file',
+            )),
             array('ktcore.validators.string', array(
                 'test' => 'document_name',
                 'output' => 'document_name',
             )),
+            array('ktcore.validators.illegal_char', array(
+                'test' => 'document_name',
+                'output' => 'document_name',
+            )),
             array('ktcore.validators.entity', array(
                 'test' => 'document_type',
                 'output' => 'document_type',