A new machine may be the clue here. Make sure that Microsoft Intellipoint or any other third party mouse drivers (such as Logitech, etc.) are NOT installed. These are death to all MCAD products, and completely unnecessary. Make sure they are uninstalled (usung Add/Remove Progams), and re-install the original Windows drivers if necessary. It usually isn't necessary: they get re-installed when you uninstall the third party drivers.
My beautiful brand-new HP mobile workstation was acting weird in SolidWorks after I installed Intellipoint: bizarre graphics, crashing. Removing Intellipoint was the only fix that worked. The same thing happened on my desktop when I installed Intellipoint, as a debugging experiment.
Intellipoint and all third party mouse drivers should be damned to Hell and burned at the stake.