Computer help: Optical mouse problem

I have the same problem

I was using a Microsoft Wheel Mouse Optical (USB) for several months without any problem. I have Windows XP and a Dell laptop that is docked in a Dell dock. Then the mouse started acting weird--moving erratically and acting as though I'd clicked when I hadn't. I switched to a new logitech optical mouse and I'm still having problems. Especially when highlighting text--the higlight will turn off as if I had released the mouse button when I haven't. Or, if I'm just pointing the mouse at a tab or icon the mouse will click on it on its own, often bringing me to a different window! This happens in all programs. I tried updating the mouse driver by downloading the logitech mouse software and it didn't make a difference. If this is happening with two different mice, does that mean there is something wrong with my hardware, either the laptop or the dock? What should I do?