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Firefox Locks up system when opening new tabs/uploading files to various sites

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I'm using windows 7 and since some point on my pc has a problem where when i try to open a new tab, it randomly locks the whole system. (Browser does not respond, then seconds later whole Windows 7 system locks up and is unresponsive.) Clicking on close has no effect then the whole system locks up. Checked for viruses and norton did not detect any viruses. Using CTRL + ALT + DELETE does not allow me to shut down firefox.

Asked in bugzilla and the answers there are less than helpful, they simply call me to uninstall firefox and test the nightly browser. I've found the problem exists in the new tabs images section where the thumbnail of a frequently visited site was causing the system to lock itself up. Then i disabled the images and so far the new tabs worked properly. However, firefox can still lock the system up when i upload word files to fanfiction.net. Any suggestions?

I'm using windows 7 and since some point on my pc has a problem where when i try to open a new tab, it randomly locks the whole system. (Browser does not respond, then seconds later whole Windows 7 system locks up and is unresponsive.) Clicking on close has no effect then the whole system locks up. Checked for viruses and norton did not detect any viruses. Using CTRL + ALT + DELETE does not allow me to shut down firefox. Asked in bugzilla and the answers there are less than helpful, they simply call me to uninstall firefox and test the nightly browser. I've found the problem exists in the new tabs images section where the thumbnail of a frequently visited site was causing the system to lock itself up. Then i disabled the images and so far the new tabs worked properly. However, firefox can still lock the system up when i upload word files to fanfiction.net. Any suggestions?

All Replies (6)

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Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

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Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen or hold down the Shift key) to see if that has effect.


Do a malware check with several malware scanning programs on the Windows computer.

Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure you update each program to get the latest version of their databases before doing a scan.

You can also do a check for a rootkit infection with TDSSKiller.

See also:

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I've did multiple malware scans with norton and nothing suspicious came in. Safe mode i can still consider. However, it does not happen, at least before i enter chatzilla. It also no longer happens when i opens a new tab, because i disabled the thumbnails. However, uploading files might still lock the system.

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Norton and other protection may not detect malware. Please use some of the above scanners. They are free to use.

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I've scanned with those softwares and nothing seems to be shown. According to other witnesses in my report in Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1361634

It seems to have nothing to do with viruses, and happens when you upload a file or open a new tab, although i had managed to make it not happen when opening a new tab by hiding thumbnails.

It also does not happen in other browsers: Only firefox. Other browsers do not seem to have this problem.

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i also get this problem as well, locking up the whole system and i have to manually re-start the computer

i'm not on windows though, im on linux mint 18