[FerdFerd]

For what it is worth as perspective, when I installed Intellipoint 5.5 the first time, I just installed it over version 5.2. When I later deleted it through the control panel, I found there were two directories left over in my Program Files directory: Microsoft Intellipoint 5.2 and Microsoft Intellipoint 5.5. I deleted both of those directories and their contents and then rebooted. At that point it seems that I had the default Windows mouse drivers active. (I had no problems with MA2.0 at that point in a brief test.)

Interesting to me was that I had always assumed I needed the Intellipoint drivers to take advantage of the extra mouse buttons on my Intellimouse. Not so - they worked for foward and back browsing without the the Intellipoint drivers. The drivers do add extra features and customizations, though.

I then reinstalled Intellipoint 5.5. I now have two directories in the Program Files directory: Microsoft Intellipoint (no version number) and Microsoft Intellipoint 5.5. So I assume there must have been some 5.2 files left the first time I installed version 5.5 without first deleting 5.2.

It is still a mystery why version 5.2 works fine with MA on some machines and not others. But for those with troubles, deleting Intellipoint drivers completely and reverting to the default Windows mouse drivers, or deleting Intellipoint completely and reinstalling Intellipoint version 5.5, seem like the first things to try now.