No particular experience with laptops here, other than knowing that sometimes the internal mouse can cause conflicts with the external.
Here's what I would try though, and it's just general troubleshooting, not specific to your problem. Do a scanreg /restore. Also see if you get a mouse in Safe Mode. To try either you must first boot to the "Startup Menu" by pressing and holding the ctrl key immediately when restarting (or tap f8 repeatedly). When you get the numbered menu, choose the "command prompt".
At the c:> prompt enter:
scanreg /restore and use your arrow keys to select a started registry dated prior to the problem from one of the first 4. The 5th or last on the list cannot be used.
You will also see "safe mode" as an option on the startup menu, try that next if scanreg /restore doesn't work.