cool feautre in Process explorer.
I had a scenario where i was getting a random popup from some exe. Was not able to make sure which process was actually the culprit as the error message was also bit misleading. Task list before and after closing the popup was also giving the same list. Event Notification Application: Unable to register with Framework, Program will not exit.
So finding out which process is causing this turned out to be very simple.
Use a tool, process explorer (https://technet.microsoft.com/en-us/sysinternals/bb896653.aspx). It has a cool feauture, you can drag and drop your mouse to any window and it will show the corresponding process.
Thats what we did and we had the culprit in just 2.2 seconds :)