I have this problem and I realised it is when I run any Microsoft product at the same time. When I have Microsft Word for mac, Excel, etc. open, I get this bug. Simply quit them.
I have this really annoying issue where my mouse will randomly double click in OS X when i didn't actually double click my mouse. I had this problem before in Leopard (with different mouse) but now it seems the problem has returned with snow leopard. has anyone else had this problem? I checked the mouse properties and there's nothing strange there. I also don't have custom drivers installed. Just default snow leopard drivers.
[doublepost=1534452831][/doublepost]I had a Kensington Trackball which was doing the exact same thing. I read a bunch of boards and nothing worked. I threw it away and bought a brand new one. Problem solved! Turns out it was a hardware issue. I have read that other people with the same issue have discovered it is not software based too. Good luck