Michel,

>Yes, he is aware.

One other diagnostic approach that occurred to me is this: You need to track every hit for awhile in terms of the PID of the EXE that took the hit, and exactly what was requested on each hit.

If, as you said, the EXE does not even receive the request after the problem begins, the log should then show you the LAST action taken by that EXE before the problem started. That may give you a clue about something that could be scrambling something inside the EXE's runtime environment.

For instance, does it always appear just after a search on certain parameters? Or just after 4 searches in a row? Or just when a certain condition being tested triggers a certain piece of code?

The last action(s) by the EXE should narrow down the circumstances related to the EXE. You might also want to check the amount of RAM at the time, etc...