just built a pc but had some problems

[gamemar]

ok first of all ill tell u the specs

2.66ghz dual core 2 duo intel E6750
p35 ds3l gigabyte mobo
7200gs gigabyte geforce 256mb graphics card
2 gigs of ddr2 corsair ram
320gig western digital harddrive
asus lightscribe dvd cd writer

ok i installed everything and it was working a treat then I left it downloading while i was at school when i came back I found that my cpu fan was not spinning, from that point i paniced and turned of my pc

but after turning the pc back on the fan turned on then went off then i went into a game and it went back on so is this some normal power saving thing ?

also when i got the guy from the pc shop to install the processor [i didnt trust myself]
he didnt apply coolent paste [is that safe he didnt look profeshinal]

and 1 last thing I went to put in a ps2 keyboard and when it was in my mouse stoped moving and my mouse is usb then i reset the pc and then it was like my pc reset. The icons on the desktop were gone, it had the original background, and my intenet setting were all defult??? any help

thanks if you read this and sorry about the bad english and spelling 

[patio]

Arctic Silver's Site has excellent instructions on applying Thermal Compound...

Running without it will fry your CPU and possibly damage other components as well.

You should also never plug in or remove a PS2 device while the machine is on...hopefully after a few cold boots with the device unplugged it will recover. Then power down hook it up and power up again.

As to the repair guy i would find someone else in your area...he doesn't need to risk damaging any more equipment.