How can I return to using Parallels 2.5?

@Greg
brkirch is not talking about installing Parallels on OS X, but rather the windows side of Parallels - referred to as Parallels tools.

This software is responsible for relaying in/output between the host and the VM and also for setting up and running the correct drivers for your virtualized hardware.

Seeing as the problem with your mouse is probably driver related - a reinstallation of the Parallels tools after a downgrade of Parallels makes perfect sense.

 

I installed Apple's free Boot Camp version 1.4, and the good news is that ArcMap works fine with Boot Camp. So I am looking for a solution to the problem that under the paid upgrade to Parallels 3.0, the Windows application ArcMap will not start up, not even one time.