Hangs At "Loading Operating System" Screen After Random Reboot

[EpicFruit]

I was browsing through some college classes yesterday when my system randomly decided to reboot itself. It was as if I had accidentally hit the restart button, my system began to close out programs and shut down all on its own, and when it rebooted, it got stuck at the "loading operating system" screen. I have run a virus scan and CHKDSK on my boot disk via HDD dock connected to another computer, neither turned up any issues, and all the files are intact and accessible. I then ran a disk restore from the other computer, but still got no results. I can't get into the advanced boot options for safe mode because pressing F8 while booting has no effect.

 

I'm running Windows 7 Home Premium 64 bit, and the boot disk is a Samsung 830 Series 128GB SSD. Unfortunately I do not have a Windows 7 disk so I can't do a repair installation. I highly suspect it's a corrupted system file. Got any suggestions?

[gts250ftw]

make sure the cpu isnt overheating? 

[EYCEthebest003]

try to boot up in safe mode and check the registry.  see if anything looks out of the ordinary or if something happened around the time when it all started.

[EpicFruit]

The CPU is at 34 Celcius according to the BIOS, and I have not been able to get into safe mode because the system does not respond to the F8 key upon booting.