Freezing computer in normal but not in safe

Hi

I built a costum pc a few days ago and i had a few problem with installing the windows because everytime it got throught the installation the screen turned off.
After i succesfully installed the pc with an other monitor it worked fine with that monitor for a few days but i had to give back that monitor.
with my monitor after the windows loading screen it didnt want to work and gone to sleep mode.
it worked fine in safe mode.
i changed settings on the pc and the monitor but if i turn on the pc in normal mode after i log in its freezes 10-15sec after i logged on.

any ideas how can i solve this?

 

System specs please.

 

Specs:
cpu: AMD 6300FX
Ram: 4GB 1333mhz something
hdd: Barracuda 7200 500 gigabyte
GPU: Nvidia GT 8500 1gb edition or SLI
PSU: ace 750W black edition
OP: win7 ultimate 32bit

 

Have you updated the software for the video card.

http://www.nvidia.com/Download/index.aspx?lang=en-us