It sounds like heat could be causing an issue.. Have you tried removing the cover and using compressed air to blow out the dust from around the processor, the heatsink, the power supply, all vents, and all fans? If not, please do.
And then, enter the Screen Saver/Power settings and change it so Standby isn't an option..
Hope this helps.
My computer recently began to have a problem whereby the monitor will go into standby mode for no discernible reason. A few days ago I was playing a video game when the screen suddenly went into standby. After some trial and error I determined that the screen would go into standby mode whenever I launched a graphically intensive application, in my case any video game. I was still able to use it to browse the internet and for other non-graphically intensive uses. The next day I tried to play a game and it worked for about 60-90 minutes before the screen went into standby. I went back to using it solely for everyday usage.
However today, after using it for non-graphically intensive things, when the desktop launches it goes into standby almost immediately. I am able to use the computer in safe-mode without problems. I removed the graphics card drivers and reinstalled the newest version (which were the same that I uninstalled), and the problem persists. The drivers had been updated in October and I had been using it without incident until several days ago. I'm at a loss about what to do. I have changed no hardware and I also did a scan for virus and adware. No fans have broken and the room temperature has not changed significantly.
Sorry for the length.
MSI P6N SLI Platinum
2GB CORSAIR DDR2 SDRAM
ENERMAX Noisetaker II 485W ATX12V
GeForce 8600 GTS 256MB pci-e
Samsung SyncMaster 226BW