Hi There,
I have had similar issues to previous posters. I have added the file using STSADM and enabled it in Operations.
I have reviewed the default Web.Config file as per the Technical documentation and it has the WebPart listed under the SafeControls list with Safe=True.
I noted another web.config file listed in the wpresources directory (it is the webpart listed in this directory, so I have renamed it to web.config.old and given all rights to all users to the image directory within it.
It has an entry in the Web.config file of trust level = WSS_Custom not the Medium or low...
Any ideas as to what to try next?
Cheers
Chris