First of all, you are using something not supported anymore
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It could be many things. We faced a similar problem whenever a certain userid logged on via mstsc to the dbms server. This was caused by the userprofile and incompatibility with some HW Drivers.
Unless you already did:
- Doublecheck db2diag for errors
- Look in Event Viewer for errors/warnings in the same timewindow as the service fell down
Look at any dumpfile and see if you reach a certain memory segment when the crash occurs, perhaps you have a HW failure either in memory or a sector on your HDD.
What about windows updates, new usecases from the clients etc.
It's a bit work to figure out if you're unable to reproduce it, but detailed work and elimination will get you s few steps up.
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