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Something claiming to be Firefox has locked the screen of my computer and can't be cancelled. Amounts to a denial of service attack. How can I tell?

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  • Last reply by FredMcD

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This is a windows 7 machine. Something, maybe firefox, is trying to install software on it, and the currently running firefox is asking whether to allow it. I'd really like to check whether it firefox or not, but if I choose "don't allow" and then cancel the install, the cycle just repeats. This locks the screen unless I allow the "update", which is suspicious. This looks like malicious software and a denial of service attack.

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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 Security Essentials is a good permanent antivirus for Windows 7/Vista if you don't already have one. Windows 8/10 have antivirus protection built-in.

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

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A way out of a trap page is to (force it if needed) Close Firefox. Wait about 20 seconds for Firefox to finish closing. Right-click on the Firefox icon and select Open New Window. +++++++++++++++++++++++++++++++++ Sometimes this works. If it opens, close it by Menu > File > Exit. This will flush out that web page from the Session Store.