I have a very weird problem with a WPF ComboBox. On one computer (and only one) in our company the WPF ComboBox refuses to respond to mouse events when the ComboBox drop down is
Well after formatting the computer and installing everything fresh, we still had the issue. It sounds silly but we replaced the video card and it fixed the problem. We even threw that card in another computer and it encountered the same problem. We also found an old driver, thinking that might be the culprit, but it still had an issue. So in case anyone else out there is having weird issues with WPF on one computer, try replacing the video card. It just might fix it.
I had a similar problem on Windows 7. Another idea is to play around with the display settings. My solution was to set the program to run with 256 colors using the compatibility settings of its shortcut.