FRM-40735: ON-ERROR Trigger raised unhandled Exception

hello,
we installed Oracle-Client 8.1.7 on a server with Windows 2000.
Th developer 6I are on Terminal-Services and Citrix Metaframe W2K.
The Forms-Applications are on a fileserver.
10 users had started the applications on the Citrix-Server and they
could work fine. After some hours when they changed a module within
the programs they received the following message:
"FRM-40735: ON-ERROR Trigger raised unhandled Exception
ORA-06508."
When I try to start an oracle-program (ifrun60.exe)on the citrix-server I receive the same message.
When i try to start the oracle-program (ifrun60.exe) by a
RDP connection i receive the same message.
Starting the same program on a fat PC then all is ok.
We have 8 citrix server with the same configuration. When a server Freeze the others continue to work without problem.
When i kill the ifrun60.exe on all the user-sessions on the citrix-server, i can start the same program without problem on the server.

The oracle Datbase is 8.1.7
The Dev 6i is at level patch 12
The Windows 2000 server is SP3
The Citrix ICA is Metaframe 1.8 SP3

If you can help me !

Thanks