There's something wrong with my computer!!!!

goku1234567890

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I think there's something wrong with my computer. Two or three weeks ago my windows 7 just hanged & nothing was moving i restarted my computer but after the "starting window" part the whole computer just restarted i removed windows 7 and then installed windows xp (local copy) after a week or two that windows again showed trouble. The whole screen went and black and then it showed the message that your computer had crashed or something like that i then again installed a clean windows but this time the original one!!!!
I am just suspicious about my computer that if there something wrong with it. No computer just show these messages or do things like that just for fun. If you guys know the problem then please help!!!!

Here are my PC specs just in case if you want it or anything:

Intel Pentium 4 3.00 GHz
1.5 GB of RAM
112 GB of hardisk
256 Mb of Graphic card(ATI Radeon HD 2400 Pro)
Windows XP Service Pack 3

Thanks in advance!!!!!