Start up problem...

Hey, let me get right down to it. Recently, my power supply went out so i took my computer have to where i got it from. 3 days later i went to pick it up and found that i had a 500W power supply rather than my old 430W. So i get home, plugged my computer in, and it turns on and just after XP is loaded and is headed to load Explorer, the computer turns off. I tried a couple times and i got it to work once for about 20min before it shut off. In safe mode, it works fine, no shutoffs. Can someone help? I am running WindowsXP SP2 and if you need any other specs just ask.

 

How are your temps?