EN7600GS blanks out screen for 2-3 sec intermittently

[elvf]

I've build new rig

E6600 + D975XBX +2Gig of Partiot RAM

Graphic card is fanless EN7600GS from ASUS.

There is a strange problem:
the screen is blanked out (as if resolution is being changed) for 2-3 sec.

It happens very irregularly while something as mundane
as Web Browsing is going on.

I've got WinXP SP2 and Samsung 204B monitor with 1600x1200 resolution.

What might be the problem?

 

[elvf]

The temp varies from 69 to 79
ASUS "SmartDoctor" (applet that monitors the card temp)
says it will slow card down at 120 degrees.

All setting in the system are default.