Monitor turns off during games

I have a mega annoying problem. When I play for example Call of Duty, FarCry, Team Fortress 2, etc. the screen turns off just after approx. 5 minutes. The computer runs on with the sound and everything, but with off screen. Only way is to kill it and restart. I have no option to turn on the screen again.

My machine is an HP with an AMD Athlon 64 processor 3500+, 1GB DDR, 250 GB Hard Drive. Graphics card is an ATI 4850 (brand new) and a Corsair TX650W power supply (brand new). My monitor is an HP Pavilion f1723 with a resolution of 1280 x 1024.

I do not know whether it has anything to do with the problem, but I have also seen that loading time is very long. Sometimes it takes eg. 5-10 minutes to go into a level.

It is annoying that the screen turns off and if I can help I will be extremely pleased.

Have you tried to update drivers?

Yes.. I went in to ATI's site and downloaded graphics card driver for 4800 series. Is it not just what you ought to do?

@ Shutdown

Team Leader's latest post is misunderstood by you. You must enter HP's home page and not ATI's home page, to download drivers. There are also drivers for your chipset and sound card, among others.

Now I have updated my motherboard and my sound card drivers but the display still shuts off during games.

Do you have a DVI cable mounted between the screen and the PC (white connector)? you have the driver for your monitor installed?

Between the PC and monitor, I have a vga connector with a DVI adapter into the PC end. Have vga dvi at the screen and the computer.

I have the driver for my monitor installed.

Thought there was a DVI input on the screen.
Have you tried with another monitor?

Could it mean something which cable to use? I have not tried with another display, but may do so as soon as possible. But is that screen there is something wrong with?

DVI is better than VGA. That the screen is just to use the exclusion method. I would try to borrow another monitor to try it on your system.