Thanks for your reply.
I've also reported this issue within Oracle, they replied:
Probably an issue with XSLT.
OM IS CRASHING WHILE ACCESSING THE VIEW WHICH USES XSLT TRANSFORMER] which looks the be the same issue you are facing.
According to OPA dev., they are looking at fixing this in the next Siebel connector release. Currently there is no workaround.
So i guess we have to wait....?!