DV4T-1400 lock up and freeze with a "click" sound after an hour of operation

[txbirdie]

We have a DV4T-1400 that was purchased in August for back to school.  Right after we got the PC it worked fine but had a constant problem of locking up and freezing after an hour of operation.  The lock up would be right after a loud "click" sound similar to someone clicking an old ball point pen.  We sent the PC to HP service in September and they replace the heat shield and returned to us.  Right out of the service box the same problem with lock up and freezing occurs immediately.  We contacted HP service again and sent back for repairs.  This time HP service returned the PC back to us stating that they cannot duplicate the problem and feel that it's a software issue and nothing was done to this PC.  We were pissed but decided to wait to see if a WIN7 upgrade would solve the problem.  Well after upgrading to WIN7, the PC still locks up and freezes with a loud "click" sound.  So the consistent problem is that the PC locks up and freeze usually after it's hot (after 1 hour of operations), before locking up and freezing there is a loud mechanical "click" sound from the PC, the only way to shut down and restart the PC after lock up and freezing is to hold down on the power button (control alt delete doesn't work).

I'm frustrated with HP and not happy with their service or this PC.  Is anyone out there experiencing the same problem on tthe same PC?  Please help!  Thanks.