Problems while using 2 Monitores

Hello,
my son is 3D-Student in Madrid and is using Maya 7 to work on his projects.
He has a brand new PC , Quad-Core 6600 and a Nvdia 8800 GTX. Everything running
under WIN XP Pro 64bit 

While working with maya and 2 LCD's connected via DVI-Cable 
(configurated as 1 big Desktop) the image will start flickering after a few
minutes when he presses the "ALT" key to change point of view.
No way to stop this  without reboot.

Maya is the only program with this behavior, everything else works great.
The problem is that he has no www in the house where he lives in Madrid and so
no chance to find any solution online.

Any ideas how to solve this problem?

Greetings from  Tenerife