So, problem solved, right? Clearly, it was either hardware or driver issue with the mouse; most likely, hardware issue, as GX1_MAN said.
I had a problem with my Logitech wireless mouse/keyboard combo last year after replacing my hard drive and freahly installing Windows. I had downloaded the latest version of Logitech's SetPoint software, but was experiencing some erratic freezing of the mouse. I uninstalled that version of SetPoint, went back to the version that came on CD with the mouse/keyboard, and the problem went away.