Issues with some OAF pages in R12.
Solution: Note ID "How to Diagnose an 'You Have Encountered an Unexpected Error" (Doc ID 562796.1)"
1) Login from the front end.
2) Enable Debug for your session to collect the trace file for the infected OAF page.
To Enable Debug, launch any form, in the form Help --> Diagnostics --> Debug
3) Now Access the OAF page that is having the issue with, for next steps you can follow the Note ID.
