I wanted to post this in the case anyone else is having the same issue with WPE erroring out and stopping. After researching many forums, I found a simple, effective solution.
Please note that this solution does not address the root cause for the WPE error and stoppage. In each case the WPE stopped, it restarted with no issues. Seems like a potential server software bug.
We created a BATCH file (Start_WPE.bat) containing one line:
FMSADMIN START WPE -u AdminUserName -p AdminPassword -y
Using the Windows Task Scheduler on the server, we run this script every 1 minute on the minute.
If WPE is running, it just returns "Service Already Running" and does nothing
If WPE is stopped, it starts it. (Try stopping the service and waiting a minute to watch it restart.)
BIG NOTE: Do NOT use the FMSADMIN RESTART WPE command. This appears to stop WPE then restart it which kicks everyone off.