Help needed (Comp random shutdown)

[colinm1]

Have a problem with comp shutting randomly shutting down for no reason

When I reboot I get message " OVerclocking Failed" please press F1 to enter Bios, press f2 to reset bios to default".

I have never overclocked my PC so do not understand this, has happened 3 times in last 24 hours.

No new software has been installed and the only hard ware change was an upgrade pf my PSU to 500W about 2 months ago.

Have never seen this message before and am stumped, would really appreciate any help or advice.

My specs are:

Pentium 4 - 3.2 Ghz
Asus P4P800Deluxe mobo
1Gb dual channel Ram
500W Antec PSU
Nvidia FX5900XT Graphics
80Gb IBM Deskstar 7200
60Gb Maxtor Diamond 7200
Audigy 2 Soundcard
Toshiba 16x DVD Rom
Pioneer 110d 16x DVD Writer
Samsung Syncmaster 970P 19" TFT

Windows XP Professional +SP2

Thanks