Sometimes (3 times now, intermittent), when i turn on my computer it makes a loaud buzzing/humming/shaking noise (Other than the usual fans or HDD noise).

To fix it i just turn off and on and it seems ressolved.

Is this just part of the joys of having a computer, or something wrong? (Loose bearings, etc...)

I'm running:

- Intel Cor2Duo E6550
- NVIDIA GeForce 8600 GTS
- 370GB IDE HDD (WDC WD4000AAKS-00TMA0)