I found an earlier discussion with:
Have you set the Alert Engine service to interact with the desktop in the service manager?
Administrative Tools -> Services
Double click on SolarWinds Alerting Engine
Select Log On tab.
Check the box that says "Allow service to interact with desktop"
Then restart your service.
I have confirmed this setting and restarted the service several times now. I still cannot get the external execution or log the trap to a file to work.
Are there other setting that affect these functions that I might have missed?
It does indeed sound like a service account permission issue. Support ticket would probably be the quickest route to get this nailed down.