I thought it might be nice to have a thread of solutions to any problems you get and fix, in case anyone has it in the future. Then they can just search this thread.
Bluescreen of Death (BSOD) nvlddmkm.sys
I would get this when booting up under Windows 7 x64. Turns out it's a driver issue.
Fix
Go to C:\windows\system32\drivers and rename nvlddmkm.sys to nvlddmkm.sys.old. Go to the nVidia directory (Where you chose to extract the nVidia driver when installing) and find the file nvlddmkm.sy_ then copy it to windows\system32. Using the cmd window change directiories (cd C:\...) to system32\drivers and type:
EXPAND.EXE nvlddmkm.sy_ nvlddmkm.sys
With the manually expanded nvlddmkm.sys file in place, the problem should be fixed next time you restart your computer.
Notes
The problem is that your current nvlddmkm has outdated information directing your computer to an old file that isn't there anymore. Uninstalling/reinstalling your display drivers doesn't fix this problem, and it has to be done manually. No idea why.