Steam Still Must Be Running

I've read just about every thread on here about this problem and I've tried everything that was suggested in the threads. None of them worked. The weird thing is that I played this game yesterday and it ran perfectly with no problems at all. I haven't messed around with any of the files. Anyway, I've tried:

Deleting Config files in C:\Users\Name\Documents\My Games\UnrealEngine3\
I checked, and nothing was read-only, so that fix didn't work
Made a backup of all my ini files and tried to launch it, that didn't work, I had steam redownload them for me and I tried running it again, that didn't work
I haven't modified any files by hand at all, so that's out of the question
Deleting both the Patches and the Config folder
Running the game as administrator
Uninstalling then reinstalling
Tried deleting the clientregistry.blob thing

None of those worked.

EDIT: Now I just have a runtime error. It's odd, whenever TF2 gets the "Welcome back, UNKNOWN" bug, this game gets the "Steam Must Be Running" bug. Maybe they're related or maybe it was a coincidence (or maybe you already know this and I'm just derping), but I think I can handle it from here >>

EDIT 2: Nevermind, the usual runtime fix isn't working for me now. :/