Odd boot problem!

So i have my old stinker of a desktop that was working fine then one day i turned it on andit flashed the ASUS screen and the show of a few misc. screen shots of hardware tests and then go to the Windows XP load screen. Well the other day it would do this and then just keep cycling it would't go to the log in screen so i tried "safe mode" and the same thing happend. So after much thought and look over of the unit i came to the conclusion that my power supply was bad so i changed it. Same result but the diffrence is that it will go threw and load up in safe mode and work fine but not regular. Anyone got any idea's?

So today when i was trying to get my computer to work when i was in safe mode when i was going threw the control panel and try to just use general things after about 30 seconds to a minute it would crash and then say an error occoured anyone have any ideas/exspericnes(sp)????