Data Execution Prevention, does changing from command prompt work?

Nakkisoosi · 19 Feb 2020

It seems to work, but does it really? Task Manager says: no.
This command shows your DEP status.
WMIC OS Get DataExecutionPrevention_SupportPolicy
For me it returned value 2, which is the default Windows 7 setting. I read that this is how it should be:
0 – DEP is disabled for all processes.
1 – DEP is enabled for all processes.
2 – DEP is enabled for only Windows system components and services (default).
3 – DEP is enabled for all processes except for excluded programs and services.
Because I have problems to uninstall and to get Firefox and Thunderbird application windows open (instead of just processes starting), and looking at Task Manager, they had DEP enabled, I decided to try and change it. Gave this command in elevated rights command prompt:
bcdedit.exe /set {current} nx AlwaysOff
Rebooted the computer.
Now WMIC command returned value 0. Which means DEP should be disabled for ALL programs and services.
HOWEVER, looking at Task Manager (need to have DEP column added to view) Windows' own programs seem to have still DEP enabled. While most non-Windows (or non-Microsoft) programs have DEP disabled.
What?
This is weird. How is it not disabled with every program now?
And for me a problem because somehow with Firefox service it is enabled, too. Even though it's not Window's own program.
How can I get DEP off of Firefox's back? Uninstalling and installing it again does not do it.

LMiller7 · 19 Feb 2020

DEP configuration options only apply to 32 bit processes. For 64 bit processes DEP is always on and there is no provision to disable it. DEP predates 64 bit Windows and all 64 bit compatible systems support DEP. 64 bit processes must be compatible with DEP. Documentation often doesn't make this clear.

iko22 · 21 Feb 2020

Nakkisoosi said:

Because I have problems to uninstall and to get Firefox and Thunderbird application windows open (instead of just processes starting), and looking at Task Manager, they had DEP enabled, I decided to try and change it. Gave this command in elevated rights command prompt:

How can I get DEP off of Firefox's back? Uninstalling and installing it again does not do it.

Cant think why DEP would cause problems with Firefox opening. Are you using the latest version of Firefox? Had you tried performing a Clean Boot, and then open the browser?

Nakkisoosi · 02 Mar 2020

Appparently DEP is not the problem. Because I can kill some processes while DEP is enabled.
And thank you LMiller7, I think you are right.

Something else is the problem. I have problems with several programs leaving zombie processes. Firefox was doing this too. They are seen in TaskManager and the error message trying to end the process is: access denied. For example games that used to work, but now suddenly won't, and Thunderbird. Some of these programs did not open a visible application window, some did but after closing the application, the zombie process is still there.
I have full rights to the file, I can take the ownership, and I can even delete the file (while the process is still listed in TaskManager), but the process is still in Taskmanager and can't be killed with any process killing command or process killing applications (I've tried many: Taskkill, PSKill64, Process explorer, NIRCMD). Hence I think it is a zombie.

I said "Firefox WAS doing this too" because now my Firefox works. Thunderbird still does not. What I did before Firefox started working was: uninstalled Spyware Blaster, found another parent.lock from a Thunderbird folder and deleted it (strange, how could this cause Firefox problems?).

Nakkisoosi · 02 Mar 2020

iko22 said:

Cant think why DEP would cause problems with Firefox opening. Are you using the latest version of Firefox? Had you tried performing a Clean Boot, and then open the browser?

Yes, latest version of Firefox, downladed it couple of days before posting the comment.
Clean Boot? You mean shut down? Yes, the computer had been shut down a few times.
However, I have another thread https://www.sevenforums.com/installa...3=#post3461317 that is related to Firefox & Thunderbird and other applications suddenly having problems. So I won't go to into those issues here. DEP was one thing I thought might be the culprit, and since DEP disabling seemed to work very strangely, made a thread just about DEP oddities.