Weird I get the same thing going on, but found this info
Problem
When the BlackBerry Controller is restarted,
or the log cycle restarts, the following error is logged in the Application log:
[CFG] Controller won't generate userdump files. Userdump.exe not found.
Cause
The BlackBerry Enterprise Server is configured to use the userdump.exe when an error occurs.
Resolution
Download and install User Mode Process Dumper 8.1 utility from
Microsoft Corporation.