First make sure you have the three essentials: Anti Virus, Anti Spy ware, Firewall.
The problem itself... optical mice can sometimes 'skip' depending on the surface they're used on, but your problem seems much worse.
All I can suggest is make sure your Operating system and all Anti-Vi/Sp is up to date. You've found several(?) viruses last week and I very very rarely ever see a virus on my system unless I've forgotten to update for a period.
Through your firewall settings you can disable certain services such as remote desktop or remote assistance which are there to allow a tech support to remotely control your system... if you haven't updated there may be a security loophole.
Try removing all exceptions for the firewall, or 'lock-down' if your Anti-Vi has it to see if this helps.
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Only other thing I can think of (on a lighter note)... could a mischievous person have connected a second mouse to your computer?
UPDATE:
Another user has posted on this answers thread:
https://answersrip.com/question/index?qid=20071011080300AADkrxO
About a possible threat when using certain animated cursors. An Update patch has been released by microsoft. Not sure how recent but this sounds a likely cause.