Neik e has a good point, I would open the case and see it there is any obstruction to the fan.
You might also try starting in safe mode and run chkdsk. If you need instructions go here
If you have access to another computer try installing the hdd as a slave and see if you can access your files. If you can and the noise persist start copying you files because this is the sign of eminent failure.
Do not open the case if its still in warranty - just send it back
Also, never ever poek about inside the PSU fan or you may die
The fan that was mentioned was the HSF, not the PSU fan.
As for the dangers of shock from the PSU, the danger is with the capacitors which can hold a decent amount of voltage for a very long time and can give you a nasty jolt. You have to remember that it's not the voltage that is dangerous to the heart, it's the amperage. The capacitors that I've seen in PSUs have all been pc mounted with the leads being accessible only if you remove the board, basically you would have to work at getting shocked.
Electric livestock fences have an output of 10000V, the voltage by itself isn't usually fatal, but under the proper circumstances it can be.