Builder Crash in windows 2008 11gR2

Dear Experts,One of my client had his Oracle Forms/Reports Services upgraded to 11.1.2 (11gR2). When he tried to open reports using reports builder it crashed while navigating through the Data Model with the following error

Problem signature:
Problem Event Name: APPCRASH
Application Name: rwbuilder.exe
Application Version: 11.1.2.0
Application Timestamp: 4e8c21a7
Fault Module Name: VGS.dll
Fault Module Version: 11.1.2.0
....
....
...

Not sure how do I get to work this for him. Can someone help me out?

Thanks,
KA