A .tmp file is a temporary file.
Likely some app or utility is trying to create the .tmp file and failing.
Look in Reliability History/Monitor and Event Viewer.
Either one or both tools may be capturing some related error. Errors can be clicked for more detailed information. The details may or may not be helpful.
Check Task Manager > Startup. Some app or utillity may be launching and, in turn, trying to create .tmp file(s).
If the pop-ups do not immediately begin at boot up check Task Scheduler. Something running in the background may be triggered and, in turn, attempts to create the .tmp.