One of my workstations has been crap-ified by a coworker. Thankfully he's no longer with us, but the junk he installed still remains. When I log on locally into my account on this workstation, a yellow rectangle pops up on the bottom right of the primary monitor that I can't close. Because it's completely blank, I have no idea what's drawing it, and the process list is kinda long. I'm getting tired of seeing it every time I go to that computer and it's always in front of any window, so it's totally dead space on the screen. Here's a picture of the primary monitor and part of the secondary:
Although the wise thing to do would be to flatten and reinstall, I can't. For reasons. How can I determine what is drawing this so I can get rid of it?