Since all you have is the kybd. and mouse using the USB port, why not install the older variety that doesn't use USB ports, one on one. Thus whatever doesn't bring-up the ewrror message is the culprit. If you're using some fancy USB device like wireless or lighted one, expect more power required. Because the USB in question are so basic to the system, IMHO move away from USB usage for those devices if only to reduce USB load for later devices like camera and such, whatever which I'm sure may cause problems. You can use a "powered hub" then add the devices to to move away from system supplied hub power needing only USB signal strength.
Also, look into a better power supply as anything rated 300W is iffy and 350W or better is desirable. I recommend further into 400W+ as a more stable choice as flaky problem(s) like this and others can cause grieve pointing all over the system, just replace it.
good luck -----Willy
Im using Windows XP SP2 in my Intel P4, 128 MBDDR desktop.
The problem is that Im FREQUENTLY getting an error message that pop-up from the system tray saying "Pwer Surge On Hub Port. One of the USB device has exceeded the power limits....".
And in the dialog box (that comes after clicking on the tray icon) it displays "Unknown USB Device".
At that time MOUSE AND KEYBOARD WERE THE ONLY USB DEVICES PLUGGED IN TO MY PC.
How to tackle this problem?
1. Is it the problem of SP2?
2. Is it the problem of Mouse/keyboard?
3. Is it the problem of USB ports/hub?
Thx in Advance..