Thanks for that Jovery,

Interesting (?) reading. We did go hunting down this path for some time, with little success.

Eventually re-installed Oracle, and it was when we were applying the patches to take us up to 8.1.7.2.6 from 8.1.7.0.0 that we found our culprit.

Somebody (!) - well me actually, had cocked up the application of the previous patch.

So sorted that out and all is now well. Specifically the problem was with the orageneric.dll

Thanks for the input