I'm thinking the mouse issue could be a symptom and not the problem. You might look to see if your keyboard is unresponsive at the same time. This usually means some other process has priority. I've also seen it to happen with hard drive issues. A drive that goes to sleep or has an intermittent cable connection can cause Windows to halt temporarily. Perhaps your event log would show something. You can clear it and then review it after the next mouse issue by noting the time of the occurrence. Wireless mice do weird things sometimes as well. Wired mice can have breaks inside the cable sheath as well.
At first I thought it was a virus but I've done several scans..some turned up nothing, some turned up a trojan and a few other things but mouse is still messed up.
I've reloaded the drivers. I'm using XP pro 64. The mouse worked fine for the first few months..it's not that old and it works fine on the thin client pc I use for work.
I'm desperate. The mouse will not move. And then it will be fine. I've reset it. Turned it off and on. Moved receiver to a different usb port.