Is it a case of runaway blank tabs? One possible cause is if Firefox wants to download something but you instruct Firefox to handle it itself. This article describes how to clear that up: Firefox repeatedly opens empty tabs or windows after you click on a link.

If they are not blank tabs, do they look like some kind of advertising? You might have a bad add-on. These can slip into your computer as part of a bundle with other software, so I suggest starting here:

Open the Windows Control Panel, Uninstall a Program. After the list loads, click the "Installed on" column heading to group the infections, I mean, additions, by date. This can help in smoking out undisclosed bundle items that snuck in with some software you agreed to install. Take out as much trash as possible here.

Next, in Firefox, open the Add-ons page using either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

(1) In the left column, click Plugins. If you find a plugin that you don't recognize or which doesn't sound essential, try setting it to "Never Activate". (The most essential Plugin is Shockwave Flash. You can use most sites without the others.)

(2) In the left column, click Extensions. Then, if in doubt, disable (or Remove, if possible) unrecognized and unwanted extensions.

Often a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Finally, you can supplement your regular security software and "mop up" any remaining issues with the scanning/cleaning tools suggested in this support article: Troubleshoot Firefox issues caused by malware. Those are free and take a long time to run. If they seem to finish quickly and especially if they require a purchase to clean your system, you may have a serious infection. Try the specialized forums listed in the article.

Success?

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes