Here's an interesting one.
I have a user on Windows XP who is running a web application inside IE8. She has two monitors plugged in via DVI cables.
When she is working the the browser on her primary monitor, everything is fine, but when she drags the window over to the second monitor, the web applications functionality grinds to a halt.
It's not just web apps either - many applications exhibit the problem.
What I've tried
- Switching the two monitors in the OS. It's obviously not the monitor's fault.
- Confirmed that it's the app slowing down, and not the graphical rendering. The application in question actually locks up. The mouse is unaffected, and I can drag other windows on top of the problematic application.