Did it happen suddenly or always have the problem since purchase ?
* What happens if you exchange R/L buttons at the Contol Panel ?
* Try another mouse with no scroll wheel.
* If mouse require drivers, unpadte drivers.
* Uninstall all instances of the mouse at Device Manager in Safe Mode and reboot to let Windows detect and reinstall the mouse.
* Is that a PS/2 mouse ? You may have a defective PS/2 port. Try a USB mouse.
Have Win. XP with a Dell 4600. The right button on the mouse does not work. It is a standand 2 button with scrolling wheel by Dell. I have tried other mouse but all have the same problem. I have gone into the control panel and then to "mouse" but have not found a way to fix the problem. Any suggestion?