win xp pro stand by problem

[akiss 0]

i have one dell Latitude C400 notebook and the last days every time i use stand by the computer goes to stand by but when i press the power button the power led it turns on but nothink else happend.i defrag disk,upgrade-downgrade bios,install again chipset drivers ,remove -reinstall sp1 but it did not work.

any suggestions...?????

 

ps.i can not format this computer because its my boss computer.

[akiss 0]

ok.i found what is wrong.it was the video drivers(intel 830m).now it works ok