Ok,thanks.
A couple thoughts:
When adding Chief Architect to the DEP exception list,are you getting any sort of messages like this,or is it just being removed from the list with no messages or prompts?:
"This program must run with data execution protection (DEP) enabled. You cannot turn off DEP for this program."
Also,could you post the path you're following to Chief Architect when you click Add in DEP?
And after adding Chief Architect,you're clicking Apply,and OK?
If you didn't have any exceptions before you attempted to add Chief Architect to DEP,you should get a prompt that you need to restart your computer after adding Chief Architect.Are you getting that prompt?
Also,unrelated to Chief Architect,but there is a bit here about Bex errors under What is a Bex error:
http://www.alteredgamer.com/left-4-d...rash-problems/
Also,after installing Spybot,did you get any prompts from Live Protection that you recall?