LOL! Isn't that the most frustrating thing? It jerks, stops, and the mouse clicks work only half the time. Good news: I figured it out.
First let me mention that I have the Wireless 5000 Keyboard and Mouse set both at work and at home, and BOTH mice did the same exact thing, on XP SP2 32-bit and Win 7 64-bit, OS doesn't matter I did all of the suggested things... latest drivers, reset buttons, blah blah blah. Barely worked, and if it did it lasted 30 minutes. Then, out of frustration, I stumbled upon the answer by mistake:
Open your battery cover and pull out the the battery that's on the left, i.e., farthest from the laser hole. That's it. Just run on one battery, plain and simple. Both mice work and HAVE worked for almost two weeks, so I know it isn't a fluke. FYI, the BlueTooth 6000 mouse only uses one battery, not sure why the 5000 needs two. Try it and see. Make sure you DO have all the latest blah blah blah, but lastly pull that battery and enjoy your mouse.
I also have my transceiver USB stick in the side of my monitor so it's 2 feet away and in direct line with the mouse.
BTW, that also means that cost of operating the mouse just got cut in half. ;-)