n your url just append content=1. This will give you the all the webparts that are deployed. Now, you can keep deleting each of the webpart to find which one is causing issue ( ensure that you know to add the web parts back).
For example: if Url is http://localhost:9000/default.aspx, try with http://localhost:9000?contents=1
also
http://social.msdn.microsoft.com/Forums/en-US/sqlkjpowerpointforsharepoint/thread/c3dcd67c-264e-4471-97bc-8ff11033627d/?prof=required
=>
stsadm -o enumallwebs -includewebparts > C:\temp\somelog.txt
Then you can see the web part is listed under some <Web Id=... Url=...>
XML node, i.e. you know the “culprit” web site.