Windows 7: Windows 7 Keeps Hanging At Startup

I have installed windows 7 on both my laptop and desktop. Installation went fine, and they worked fine for the first few days. I updated my computer, and it said it needed to restart. So i restarted the computer and waited. But this time it said it needed to perform a disk check.



I let it do its thing, but it seems to take a little longer then i thought i would. So i went to bed, but when i woke up the next morning it said it was replacing "invalid security keys with default security keys" I wasn't to worried about it, but when i realized there was over 7000 of them, and it was only on 200. Realizing this was going to take forever, i just shutdown the computer and restarted it.

Well when i restarted it the farthest i can get is the windows start up screen with the glowing ball. I've tried using the disk for system restore, or even repair system, but i never get anywhere the system just ends up handing. Can anyone please help me out?!

Start Windows in safe mode with command prompt. Open the command prompt (cmd.exe) and type

sfc /scannow

Let that complete, then do

chkdsk /f c:

Then try to reboot into Windows normal.