How does your mouse connect ?? is it usb or a
ps2 mouse ?
Recently I have been having major issues with this and I think I fixed it 2 nights ago.
Basically I have a usb mouse that was connected to a port on the back of the system. For the last few weeks I have been having mouse freeze issues where I would keep shooting or could not shoot ( would change from each freeze event ) and I was stuck looking in the same direction until it decided to un-freeze.
I fixed this issue by unplugging it from the rear port and plugging it into 1 of the front ports of my machine.
I have no idea why this has fixed it as the front ones are just run via an extension on the inside of the case but it has. So my only thought on the matter is that it likes this other port better and has not frozen once.
I hope this is the same in your case