At work, we use Office 2007 and I had bunch of problems with. It was impossible to use the mouse to click or select or anything but scrolling.
We were 3 to have the same problems, we finally foud the sollution. We were the only one to have PowerAMC 12.5 installed on our PCs! The problem was the powerAMC plug-in for word. To solve the problem we just had to disable it.