Freeze during "Memory Testing"

[GoodRevrnd]

When the computer is booting up and hits the point where it says "Memory Testing" it says "Memory Te " or "Memory Testin " and freezes at this point. The problem started after a routine reboot. The most logical thought was memory went bad. I took my computer over to my friend's house, swapped out mem and it worked fine. I even played games for a couple hours. I brought it back home (with his memory still in) and now it's doing the same thing again.
I am using an EPoX 4GEA+ and Crucial PC2700 or Crucial PC2100. When it hits this point the motherboard LED diagnostic says '52' which means 'Test all memory (clear all extended memory to 0).' What's the problem? The motherboard? A short? Bad juju?

 

[GoodRevrnd]

OK, this is the most retarded thing I've ever encountered in my life of fixing computers... but I fixed it. I thought for a minute about the reason I rebooted, and the reason was I just installed a scanner. So I thought, what the hell, might as well unplug it and see what happens just in case this is the reason. Lo and behold, this was the problem. Why would a USB scanner cause this sort of problem???? Mind you it isn't specific to one USB slot and the printer and joystick work fine.

 

[KB]

Is the USB scanner self-powered(using an outlet) or USB powered? If the USB bus is providing the power to the scanner, then it may be draining too much juice for your power supply to handle. You can upgrade your PS, which may not solve it, or try getting a self-powered USB hub.