Operation POD issue after upgrade

Hello Experts,

Recently our ME system has been upgraded with support package 03. Before that operation execution through standard operation POD was taking place without any problem.

But after this upgrade, I am facing problem with Start (PR500) and Complete (PR510) buttons with following error messages:

Start                An internal error occurred; contact technical support

Complete         Exception occurred while executing Complete (Activity ID PR510) (Message 11400)

I do see few new rules in the activity maintenance but not able to fathom the reason for this sudden problem.

Can some one give any input on this?

Thanks in advance

Srinivas