stuck at grey screen after update

I was trying to update my MacBook Pro from 10.6.5 to 10.6.8. The update finished after several minor issues with downloading. (It downloaded a corrupted file and prompted me to redownload it). Afterwards, it restarted and now it just sits at the grey Apple logo and the spinning wheel is frozen after about 10-20 seconds.

I have tried resetting NVRAM so far and that is it. I'm new to Macs and I'm not sure what to do from here.