If I have some time when I get home tonight I'll try and look into the mouse buttons 4 & 5 working as well as the right shift key.

For the lag problem you mentioned after 5-10 minutes, is this 5-10 minutes of use where you don't move the mouse onto one of the off-screens then when you do you get lag, which goes away for another 5-10 minutes after that? If so I think it has to do with the way Windows XP pages to disk and I have a potential solution for it that I want to try out. If I get time I'll add it into the next version and see if it works.