What did you do?
You somehow managed to either rename the installer so that it's now called "md5sum NVIDIA-whatever", or you managed to create that file where it didn't exist before. Although I suppose it's remotely
possible that the unclean shutdown and the filesystem corruption that that can cause might have done that.
Plus, running something as simple as md5sum won't cause a lockup. Unless, perhaps, your memory isn't quite OK? If anything is overclocked, put it back to normal. You might also want to run a memtest86 on it overnight (www.memtest86.com