I have 2 ram sticks ,1 gb each. Intel core 2 duo processor and yes i have an graphic card installed.I am running windows xp os.
Alright. First, you should try removing one stick of RAM at a time. See if you can restart a couple of times with just one stick and check if there's no issues. If your problem goes away with the isolated stick, that means the chip you removed is bad. I'd file for an RMA with the manufacturer, if possible.
Next, if you're still having issues, make sure your video card is getting ample power. Many graphics cards require an additional 4-pin, 6-pin, or 8-pin connector from your power supply to function properly. If you have one, make sure it's snapped in tightly. Try using onboard graphics if available, or a different video card to test with temporarily.
Perform some hardware stress tests/benchmarks, see if anything is struggling. Memtest86, Prime95, Speedfan, Realtemp are all just a few useful utilities to use when testing/stressing your system. I believe Realtemp comes with a Load Tester you can use to fully load your processor, just keep an eye on temperatures.
If all this is to no avail, it's most likely a power supply.