Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

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Boot your system in safemode, by pressing F8 key on startup and check the problem exists or not

Could you check if the heat is reaching over 80 degrees C before the shutdown to see if overheating is the issue.

• www.techpowerup.com/realtemp/

Might not work on AMD but there are many programs similar to it.

The question was: "When watching a video in Firefox, the computer shuts off as if the power plug is pulled out of the wall."

The idea that there is malware on the computer does not fly when the computer is brand new out of the box with a fresh operating system installed. The problem is happening on a Dell OptiPlex 9010 with an Intel i5 processor. This appears to be a FIREFOX compatibility issue with the OptiPlex 9010 because the issue does not happen on any other computer running any version of Firefox and it does not happen on the 9010 when using Internet Exploder or Google Chrome.

The issue cannot be heat related either as the other aforementioned browsers do not have the shut-down issue and play all videos just fine. Also given, there is plenty of adequate ventilation for the 9010 so the system is not shutting down due to thermal issues (I've checked the logs and there is no indication of thermal issues).

Dell has no clue as to the cause. Because other browsers work fine, they chalk it up to a Firefox issue.

Hi Captain Jack, try disabling use of hardware acceleration for graphics in Firefox and in Flash, to work around possible driver incompatibility issues.

(A) In Firefox, un-check the box here and restart:

orange Firefox button (or Tools menu) > Options > Advanced > General > "Use hardware acceleration when available"

Note: if you cannot operate Firefox long enough to do this, start up in Firefox's Safe Mode by holding the Shift key down when starting Firefox.

(B) In Flash, see this support article from Adobe: http://helpx.adobe.com/flash-player/kb/video-playback-issues.html#main_Solve_video_playback_issues

Any improvement?

Hi Jscher2000:

No, not really. The only thing that seems to have helped (but isn't much of a help) is updating the video drivers. This is what I did:

- I disabled Hardware Acceleration in both Firefox and Flash. The system still shuts off running video. - Went ahead and downloaded latest and greatest video driver from Dell. - Tested before turning on Hardware Acceleration and it did not seem to cause a problem. - Turned on Hardware Acceleration, system turned off again. - Turned off Hardware Acceleration and tested. Problem seems to be gone.

Solution: Turn off Hardware Acceleration in Firefox and Flash. Don't like it, but hey, if it works...