Version 5 worked great for me, but after upgrading, 5.1 no longer recognizes my mouse. I have a USB Intellimouse Explorer (5 buttons). Only the 2 standard buttons and scroll wheel button were recognized by 5.1. Also, the mouse acceleration curve was way worse. I tried running the update a few times with my mouse plugged in different configurations, but to no avail. I went back and installed 5.0 and everything works the way it used to. Good thing I kept a copy.

BTW, I didn't write to bash MS. I actually gave 5.0 a good review, but 5.1 is just horrible for me. Also, I'm not happy that there's no info on "What's New".