|Seeing as you say that this doesnt happen if you boot into safe mode here is what i would suggest:|
in safe mode goto
Start > Run type msconfig and press enter
from the window that pops up go to the startup tab, deselect EVERYTHING, dont worry Windows will automatically enable everything it needs, and you can also enable everything again if you need to later.
After you deselect everything, press apply then ok. now you will be asked if you want to restart the computer, press yes, and restart.
if the problem does not appear after restart then that means that an application you have installed is causing the problem, basically when windows loads, it will load a particular application and that causes the machine to freeze.
you will then have to find the culprit by enabling apps one at a time. to be honest i usually turn them all off, apart from my antivirus and firewall.
Anyways, try this first and let us know what happens.