Computer won't turn OFF and other issues

I couldn't find a section for manufactured computers. I'm trying to get this old Dell Dimension 5100 to work.

I have several issues with this computer.

After installing XP on it and installing updates, I get this message: "Power Surge on Hub Port" Following it saying: "A USB device has exceeded the power limits of its hub port. For assistance in solving this problem, click this message.

Clicking the message doesn't help. The only devices that are plugged into the USB ports are a Saitek eclipse keyboard and a crappy wireless mouse.

The message pops up after a few minutes after the system is turned on. I've tried placing the devices in different USB ports, it didn't help. The motherboard doesn't have a PS/2 port so I can't plug in a different keyboard or mouse.

just now, I have learned after unplugging the wireless mouse for a while, then plugging it into another USB port, the message disappears for a few minutes.

Next issue:

The computer will not turn off. I've tried hard booting, pressing the power button just once, having windows shut down and not restart. The computer turns itself on after a few seconds of it powering off, like it has a mind of its own. The only way to get the computer to turn off is if I unplug it from the outlet.

I also had a constant restarting issue where when I loaded my windows desktop, the computer would automatically restart.

I've tried reinstalling XP multiple times.

Even without XP or any other OS installed, the computer will not turn off.

I don't know what's wrong. What do I need to buy

I wouldn't be asking for assistance if I haven't used google already. And I haven't read that article about 6 times already.

Anyone have a real solution and not an ignorant reply?

http://www.answermejesus.com/ask.asp

OP is troubleshooting his system with a 'crappy wireless mouse'.

http://letmegooglethatforyou.com/?q=DUH

Level 2 tech support here.

http://www.cs.utk.edu/~ffowler/jav [...] otato.html

USB power surge + automatic booting makes me think of an electrical short. If it were my system I'd check all my power cables inside, my mb seating, my ps and see if anything is bared and touching the case.

Thats just my 2 cents.