I've had an XPS 420 for about a month. About a week into owning it the monitor started going blank at random times. It's still on it just doesn't seem to be getting a signal from the computer. One second it will be fine then it just cuts out and I have to turn the computer off and on again. It sometimes will go a couple of days without doing it sometimes it will do it several times a day. At first after searching around I thought it might be a problem Vista was having with sleep mode so I stopped putting it to sleep and would just turn it all the way off. That seemed to work for almost a week but it's started again.

The PC has 

Intel Core2 processorQ6600 (2.40Ghz,1066FSB)

512MB NVIDIA GeForce 8800 GT

4GB DDR2 SDRAM at 667MHz

the monitor is a Dell UltraSharp 2407FP 2407FPW-HC.

 

Any suggestions would be appreciated