Then it's most likely not the mouse. Is there another USB port into which you could plug the mouse for a while? That could tell you if the USB port is the problem. What operating system? Are you using the mouse manufacturer's driver software?

Thanks for the response. I tried another port with the same results. I installed a wirless optical mouse and so far no problems. I'm wondering if the USB power source is failing.

It could be you have too many devices using USB ports. The computer only supplies so much power to all USB devices, then you need to buy a USB hub which has its own power.

On another note, the LED on my optical mouse always dims and brightens, for no apparent reason. It's a corded USB mouse. Only USB device on my laptop.

Thanks for the response. I have a powered hub and since I switched to the cordless mouse I've had no problems. The mouse dims when it isn't in use, probably to save on power.