I have the exact same issue as member SunRue posted about on Jan 25 2009,
Left Clicking Brings up Properties and Other Strange Phenomena
except that I determined that it not only affected my XP partition but also my WIN 7 partition.
Otherwise, I could just as well have been writing his post myself - identical symptoms.
Rebooting did not help, since It was extremely difficult to run any executeable file, including Restart.
Also Right clicking sometimes brought up context menu, and sometimes not
Definitely not a mouse problem-tried three, including PS/2 and USB.
The only thing that saved me was restoring a full drive image from day before.
I also noticed that after member SunRue was asked to run MBAM that no one ever got back to him after he posted results, so nothing was learned there.
I would like to ask if anyone else has observed this phenomenon.
Also is there any way to private message member SunRue?