Data Execution Prevention problems

Well, to start things off, I was having problems with the game Unreal
Tournament 3 receiving a "stopped working" crash. I figured out it was Data
Execution Prevention that was shutting the program down. After finding out
that I could not add ut3.exe to the DEP exception list,

(control panel/system and maintainence/advanced system settings/ performance
settings/ Data Execution Prevention)

,I decided to turn it off by typing this into the cmd and restarting.

bcdedit.exe /set {current} nx AlwaysOff

This worked, but after UT3.exe crashed again, this time with a "memory could
not be read", I figured that DEP was actually turning it off for a good
reason, so I turned it on again.

bcdedit.exe /set {current} nx AlwaysOn

That worked too, but now for some reason, the options in the DEP section in
the control panel are now greyed out. Also, it was at this time that I began
getting "stopped working" errors with not just UT3 but suddenly numerous
other games as well. I figured it was something to do with the greyed out
properties in the control panel. DEP was definitely running differently, so
I tried taking out the {current} in the cmd command.

bcdedit.exe /set nx AlwaysOn

I'm not sure if this did anything. Anyway, I have no clue how to get DEP
back to the state it was in before this fiasco, so could someone help me out?