My problem: I "accidently" deleted the NewForm.aspx and then I got the errors: If you click New to create a new item in the list, you receive the following message: Invalid page URL: If you click an existing item in the list, you receive the following error message: An unexpected error has occurred I had a backup copy of my NewForm.aspx, but it did not work to just put it back into place. (see also here: http://support.microsoft.com/kb/935504 ) I also had the field "new item form" in list properties empty (see image) and I could not fill the value. Whenever I saved a change it was empty again, when I called the properties again. Here I found my rescue: To view the original information: http://blogs.msdn.com/dszabo/archive/2007/02/20/custom-list-newform-aspx-ruined-in-wss-3-0.aspx This is just to keep the information in case Davids page might be unavailable: 1. Open NewForm.aspx and EditForm.aspx in Sharepoint Designer 2. Copy the code for the ListFormWebPart contro...