I seem to be having a problem.....

Over the past week or so my PC keeps losing the internet connection and won't find it again. I then have to restart my computer and it usually works. Someone from the internet company came out today and replaced my modem so I kind of rule that out as the problem. The other thing is when i restart everything seems fine untill i get to the screen with the green loading bar. The lights on my keyboard flicker for a few seconds then the whole thing just restarts again. This problem seems to continue forever. I just watched it restart itself 10 times before signing on in safe mode to ask this. So can anyone point me in the right direction to get this fixed please? Thanks