I have just built my first computer and everything was working fine for about a month (didnt use it everyday) and then suddenly I ran into a problem at the weekend.

I was using my computer as normal and then it crashed - a blue screen appeared then it restarted. When it came back on I sent the error report to microsoft and it said the error was possibly caused due to a device driver. I then continued to use the computer as before. A few hours later I switched it off to go downstairs. When I came back later that night, I tried to turn it on and I now get nothing on the monitor. The computer seems to be running, but I cant see anything on the monitor.

Could this mean there is a fault with the graphics card? I dont understand why it worked for a while now suddenly won't. Can someone suggest how to diagnose the problem?

My system is as follows:
Aspire Xplorer Black/Silver ATX Case
Akasa Dual Fan Active PFC 550W PSU Quad 12V Rails 2xPCIE
Asus S775 Intel P965 P5B DELUXE/WIFI Motherboard
Intel Core 2 Duo E6600 Socket 775 2.4GHz
Corsair Memory TWIN2X2048-6400 2x1GB 240-Pin DIMM XMS2-6400 CL5
Western Digital Caviar 160GB 7200RPM S300 16MB
MSI Radeon X1950PRO 512MB GDDR3 PCIE Dual DVI VIVO
2 x HP 16x SATA DVD +/-RW drive

Have you looked at your device manager to see if all of your drivers are installed and are the correct drivers? How are your temperatures? How are the temperatures of your video card? It may be a memory problem so run a memtest. Also, what is the combined amperage of your PSU? (check the side of the psu, there is a chart, just add up the amps under the 12V's)

Some problems will only show their nasty heads given specific conditions, sounds like you triggered one.

Try using a different video card, do the common stuff first. My PC died a week ago, it was the PSU, after 2 days... You said your has power so that's a good sign. Does anything appear on the LCD? Like no signal, etc? If it does then your video card may be working correctly. Check connections on the mobo, like I said go over the basic stuff first.

Keep in mind that 'no video' is merely a symptom of any number of possible problems that could keep your PC from booting enough to kick the monitor. People tend to blame the video card or the monitor when they get no video but it is usually something else. Of course it could be the monitor or the video card too. Or a loose monitor cable.

Do you hear a single short beep shortly after power up? This is the 'all healthy' signal after power on self-test. If not then the PC may not be actually booting.

Do the fans spin on the CPU cooler? Do the hard drives make healthy sounds? I take it you do not hear the 'welcome' sound from XP after it boots?

I would start with the ram, and pull on stick out, running it in the 1st bank, then switch it with the other stick of ram, to see if will POST.

How can i run any tests e.g. checking device manager and drivers when I cannot get anything on the monitor?

When I press the power switch on, with the monitor already on, I get absolutely nothing showing up - the screen is just black. When I power on and then turn on the monitor, it says No Signal Input.

I tried taking out a stick of RAM, but that makes no difference. I can't get the other stick out without taking off the CPU fan, so i'll try that later.

At power on, all the case fans, CPU fan & graphics card fan are spinning and the hard drive LED flashes, along with the DVD drive LEDs. But I don't get a system beep. The case speaker is definitely in.

One thing I guess you could try, is disconnecting the cables for the reset button, and power switch/button.

And try starting the PC with a screw driver shorting the correct jumpers that the power button uses. Might be as simple as a faulty switch.