Targus Mouse Problems

I recently ordered a Targus Laser Desktop Mouse from Dell. It is a AMU14. It "wanders" and wobbles and I can't control, especially when I first turn on my computer in the morning. For a few hours sometimes but gets better as the day goes on. Any ideas what the problem is and how I can solve it? (Doesn't need drivers installed upon first hooking it up, so likely not a driver problem...). Thnx.