any one can help with my case?

i have a laptop and suddenly did not work.
it happend first with noise from hard driver, and beep after that, then the system crashed.
later after reboot, the harddisk was missing, and bios cannot detect.
i reinstall(unplug and plug the HD), and harddisk could be found. but 30mins-1h, it disappeared again.
no virus was found, not bad sector was found, no system clash, no power problem, no compatible problem.
it was working properly for 2 months.
i would guess it is harddisk problem, it may be overburden, since it is toshiba 40G, made in china.
any other suggestions? many thanks!

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