Hi, I am new here    
I just built my new computer (w/ an E8400 EP35 DS3L 2GB OCZ 8800GT), and when i try to shutdown my computer, it shuts down and then powers up again after like 1 or 2 seconds; it does this too when i restart the computer and when i press the restart and power button on my PC. Oh yah, I'm running on a 900 Antec case. Is there anything that I did wrong or anything I need to do to fix this? Thanks in advance  

Check for WAKE ON features in the BIOS it may be set to WAKE ON mouse or keyboard..
 
also, refer to your motherboard manual to make sure you have the power switch in the correct place on the Motherboard..
 

mouse and keyboard wake is Disabled
i checked the power switch and it is correctly place
whenever i try to shutdown, it still does it, i can never shutdown without turning off the AC on power supply...
can ANYONE help?? THANKSSS

Run Folding@Home on it.  Then you have a good reason to leave it on, you will be contributing to finding cures for diseases like alshaimers and cancer.  Read about it from the links in my sig.

 
Congratulations, you totally solved the problem. We should throw you a parade. >>  
 
OP, what OS are you running? Also, when it shuts down, do all the fans stop and lights turn off, then it turns back on, or is everything still running when it boots back up?

Maybe a defective power switch. Try using the tip of a screwdriver or a jumper momentarily.

yeah when it shuts down, everything completely turns off, and then the computer turns on again after like 1 or 2 seconds
 

 
its not the powerswitch, because i took it off when shutting down and after the system competely shuts down, it still boot up after 2-3 seconds again without the power switch connected
 
 
THIS IS SO PROBLEMATIC, ANYONE HELP PLEASE  

nvm, i solved it, the mobo is gay