The Problem: when you resize the OS window, or switch to fullscreen or coherence modes, the mouse stops responding and floats down the screen diagonally to the right. I only had this problem after upgrading to build 3120, but once I had it, no amount of re-installing would fix it. Solution: Windows seems to be having a driver conflict with either the Parallels Display Driver, Mouse Synch. Driver, or both--I think it is trying to used old cached versions from the prevoius betas. Here is a workaround that solved the issue for me. I tried just addressing the video driver, but to get it to work, I had to go through this ass-backward process to get the mouse and video both playing nice again: http://www.noovibe.com/tmp/tutorial/mouse_video_fix.htm I would list it here but I wasn't sure if I could post images in the forum. Hope this helps everyone else with the same issue. Parallels Team, I think you can fix this for the release by making windows purge all the old cached drivers or something.