I have this problem with my monitor. The thing is that it randomly will go to power down! I mean im on the computer and then suddenly the screen would go black and it would say "No signal detected" then it would say "Power down". Then the screen will go black. The little monitor light will go orange. The little light on the tower will go red and stay like that. After that it will stay like that. Regardless of whatever I do it will stay like that, so I am forced to restart the computer.

Thanks in advance Did this just start? Check the display power down setting in Power Options (control panel)Sorry to tell you...this isn't a problem with the monitor itself. It is actually a problem with your computer, it is crashing, bad.

I would say it's an OVERHEATING issue but usually that RESULTS in automatic reboots, but you are getting hard crashes, where windows suddenly dies and ends up just leaving anything and everything running. (I'm leaning toward the power supply) Meaning failing capacitors and after they heat up enough, they do not work right and end up outputting the wrong voltage or something like that.

It could also be your graphics card (as long as it is not ONBOARD)

Another possibility is your RAM, you could have a defective stick of RAM, and after a while, as RAM FILLS up with programs and information, it then gets to the bad chip and errors out, windows crashes and leaves everything black.

It could also be a motherboard fault. Where maybe there is a VERY small fracture in the board from YEARS of heating up, cooling, heating up, cooling...and repeat a hundred or so more times.

In conclusion, start with the power supply, by borrowing a known good PSU of the same wattage or greater.

Then if that doesn't fix it, try each stick of ram individually, if it still happens...

Try removing your graphics card and operating from the onboard graphics.

Failing that...I would say you are looking at a motherboard replacement

Hope this helps!right.. i would recommend to do some maintenance inside your PC, especially in graphic card area, try to remove graphic card and remove any dust in it, be careful not to damage it of course, but i had same issue some months ago and cleaning out dust from graphic card (main area is under fan and fan itself) took that same issue away.
hope it helps;)