Many people who use Mozilla Firefox in Windows Vista are facing a frequent crashing problem. After 4-5 minutes their Firefox crashes and Windows Vista shows a message:
Data Execution Prevention (DEP) has shut down Firefox to protect the OS.
If you are also facing this problem, then use following simple steps and your problem will be solved:
1. Click on “Start button -> All Programs -> Accessories“. Right-click on “Command Prompt” and select “Run As Administrator“. If you are prompted to enter password, enter the password and continue. You can also open Command Prompt in Administrator mode by typing “cmd” in Startmenu Search box and press “Ctrl+Shift+Enter“.

2. Now provide following command:
bcdedit.exe /set {current} nx AlwaysOff
3. Restart your system and now you should not face crashing problem any more.
This article was posted by VG in following section: Mozilla Firefox, Troubleshooting, Windows Vista.
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Kunal
Turning off DEP is doesn't appear to be a valid solution - DEP was put in to protect the OS from malicious programs. Seems to me that FF should be fixed.
Saurabh Gupta
Nice post VG,
but der is a small problem i dont know wat is DEP exactly.
VG
^^ Its a security feature but creates problems many times.
gaby
I followed your tip and now I have a blue scree everytime I boot windows and nothing seems to repair the problem.
Chris
^^
I had the same issue, turns out Vista didn't like me turning off DEP to try to get Acrobat 8 to work :-)
To fix it without having to reinstall Windows, do this (going off of memory, sorry if it's not 100%):
Put your disc in, and load the system repair.
It might end up repairing a few things and restart the system, let it do it. It should probably continue to fail.
Restart, and start again, going through Startup Repair enough that it finally says it can't fix it. At that point you can tell it to show you advanced options. You can pull up a command prompt.
Run the command, turning it back to always on, but replace current with default, so the command looks like this:
bcdedit.exe /set {default} nx AlwaysOn
I did that and it was rock n' roll :)
Nick Myers
I have a Dell XPS M1730 which blue screened on boot after running this command:
bcdedit.exe /set {current} nx AlwaysOff
Having hunted around on the web, I thought to 'undo' my mistake of following this tip, I would just use the command to 'turn it back on'
bcdedit.exe /set {current} nx AlwaysOn
But this didn't work, I still got a blue screen. However the following did work and I'm back in Windows without having to reinstall or repair.
bcdedit.exe /set {current} nx OptIn
Thought I'd post a reply here because your site came up in the first page of google results for the terms "vista dep blue screen".
YMMV - Peace
sam
i tried it but my command prompt keeps sayin, " the boot configuration data store could not be opened,"
Phillip Remaker
Actually, this command is COMPLETELY dangerous. The whole point of DEP is to stop allowing malware to take advantage of buffer overruns and compromise your system.
Turning DEP off is the wrong answer. If the program is failing due to DEP, there is either a misbehaving plug-in or some spyware/virus/worm.
Turning DEP off just lest the malware run freely.
There is an underlying problem if DEP is tripping.
acidboy
To those suggesting that it is harmful to turn off DEP because then it will allow malware to run, I appreciate your caution. However, unlike you folks (apparently), I do not allow my computer to run malware. This is what antivirus software is for. If you have a virus on your computer, your lack of DEP is by FAR the least of your problems.
EF
In case turning off DEP causes your computer to bluescreen (as it did mine), there's a way to get it back:
- Perform a system repair using a system repair disk.
- Open up command prompt inside the repair (There'll be an option under advanced options)
- You'll be in "X:/" instead of "C:/"
- type (without quotations) "CD Windows/system32"
- type (without quotations) "bcdedit.exe /set {default} nx OptIn"
Done!