We were using the Openlink drivers as they were the only 32 bit ones available
when our project started.

I have been posting "RDO bad bad bad" type messages for several months now.  
Interestingly, Openlink bypasses SQL*Net, Oracle's own networking protocol, one
layer above tcp/ip.

Maybe it's time to start trying Oracle Objects (now in beta) which is their
replacement for RDO (assuming you are an Oracle site).

Brian R.