I have a MS Wireless optical mouse 2.0, and since I started using Blender everything has been fine. The MMB does what it should, rotate, pan, zoom etc. But just today, when I click the MMB I get switched to a new window?
Did you update the InteliMouse drivers? By default, it assigns the Switch Window function to the middle mouse button. Check in your Mouse properties in the control panel and set it back to Default action (or something like that. I can check later at home if you haven’t solved it by then).