it's a new home theatre system i put together

Asus M5A88-M board
Athlon II
4GB ram
on board HD 4250 GPU
380W Antec PS
hauppauge 2210 capture card
win7-32/mythbuntu

every 5 minutes (almost to the second!) the machine goes to sleep

symptoms: hdd light flashes, screen goes black, power light goes off
- then it all comes back up again if i move the mouse

it doesn't happen
-while watching live TV (mediaportal)
-when mediaportal frontend is open
-while running under mythbuntu

computer does wake and stays awake when a MP scheduled recording time comes around

it does happen
-when browsing the web or files on the local machine (windows)
-when watching recorded TV (through mediaportal)
-when a dvd is playing (VLC player or mediaportal)

it happens even when
-computer/hdd/screen are set to never sleep
-S3 suspend is not allowed in the bios
-Insomnia is running
-latest ATI drivers installed
-all temps are well below 35 deg

no motherboard software installed apart from drivers

if anyone can think of anything i can try...?

i have a suspicion it could be related to the on board graphics - will try with a video card

separate video card makes no difference

hey steeve, does the problem happen in safe mode?

thanks steeve

OK, tried that - no it doesn't happen in safe mode!

that could be a good sign?
maybe a driver issue

i did install the latest ati driver

mmm ,,, could one/some of the Asus motherboard drivers be causing an issue?

will look into it