PC won't restart - does mobo mess up restart function?

Hi,
I've just built a new system for my daughter, system specs below:
MB 775 ABIT I45D 945GC EXPRESS ATX DDR2
CPU 775 CORE2 DUO E8400 3.00GHz FSB1333 6MB
Cooler Zalman CNPS 8700 LED Socket 754 / 775 /
VGA PCI-E 256 MB GEFORCE 8400 GS CLUB 3D GDDR2 PAS
+ brand new PSU and 2 GB RAM

Everything works fine, have it up and running on XP, sp2, all drivers are up to date.
The problem I'm having is that the PC won't shutdown/restart from Windows XP, SP2. I have to physically press the shutdown / restart button to shut down or restart it.

When shutting down from Windows, the system actually shuts down, but the fan keeps running, and i cannot distinguish between shut down and restart.

Anyone has a clue as to what this can be about?

Thanks in advance,
Catharina

well write a command as shutdown-s in a note pad..then save it in .bat extention and click on it..and see weather it get shut down,,