I have found some documentation on this error but don't really know how to fix it. Can someone help please.
When I try and remove an ImageGallery Page I get this error, I can unpublished or delete from draft. But not BOTH....

thanks

------------------------
500//ERROR [User Error]: Uncaught Exception: DataObject::delete() called on a DataObject without an ID
IN POST /mysite/admin/EditForm
Line 1126 in /Users/mysite/Sites/jcphotography/sapphire/core/model/DataObject.php

Source
======
1117:    */
1118:   public function delete() {
1119:      $this->brokenOnDelete = true;
1120:      $this->onBeforeDelete();
1121:      if($this->brokenOnDelete) {
1122:         user_error("$this->class has a broken onBeforeDelete() function. Make sure that you call
parent::onBeforeDelete().", E_USER_ERROR);
1123:      }
1124:      
1125:      // Deleting a record without an ID shouldn't do anything
* 1126:      if(!$this->ID) throw new Exception("DataObject::delete() called on a DataObject without an ID");
1127:      
1128:      foreach($this->getClassAncestry() as $ancestor) {
1129:         if(self::has_own_table($ancestor)) {
1130:            $sql = new SQLQuery();
1131:            $sql->delete = true;
1132:            $sql->from[$ancestor] = "\"$ancestor\"";

Trace
=====
<ul>DataObject->delete()
line 81 of ImageGalleryPage.php

ImageGalleryPage->onBeforeDelete()
line 1120 of DataObject.php

DataObject->delete()
line 696 of CMSMain.php

CMSMain->delete(Array,Form,SS_HTTPRequest)
line 329 of Form.php

Form->httpSubmission(SS_HTTPRequest)
line 143 of RequestHandler.php

RequestHandler->handleRequest(SS_HTTPRequest)
line 161 of RequestHandler.php

RequestHandler->handleRequest(SS_HTTPRequest)
line 147 of Controller.php

Controller->handleRequest(SS_HTTPRequest)
line 282 of Director.php

Director::handleRequest(SS_HTTPRequest,Session)
line 125 of Director.php

Director::direct(/admin/EditForm)
line 127 of main.php

</ul>
http://localhost:8888/mysite/cms/javascript/LeftAndMain.js?m=1328047220
Line 497