Display going blank after the xp loading screen

Try to repair the os with xp cd.

maybe your graphics card has gone count?.

SO why the loading screen is there.

check without graphics card..

Do the following steps..........
check the jumper setting of the card


do you not hear beeps? they give you a rough idea of what the problem is
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Other things U need to check is compatibility of MO with ur graphics card....colling system of the cabinet.