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!

hello, please go to firefox > addons > extensions & remove any suspicious entries (toolbars, things that you have not installed intentionally, don't know what purpose they serve, etc).

Remove a toolbar that has taken over your Firefox search or home page Troubleshoot Firefox issues caused by malware

Note that the OP is on Mac, so malware scanning programs for Windows won't help.

That would be Tools > Add-ons on Mac.

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

Thank you for the information. I am using Mac OS X 10.9 system. I will try the antivirus you recommended and see if they have Mac version. Best!

I did not find any suspicious entries in the add on list.

The popup did not show up in the safe mode. If I Reset in safe mode, will my bookmarks still be available? Or I may need to backup it first. Thanks!

Hello,

First of all apologize for suggesting Windows Malware tools. I should have noticed that you are running a Mac. Thanks to Cor-El for pointing that out.

On your machine you have the following extensions. Is it possible for you to uninstall / disable these extensions and then try if the popup appears

1. Pin It button 1.1
2. ShareThis Toolbar 1.300.436
3. Shop.com Community Toolbar 3.20.0.4
4. ShopBuddy 1.0.24
5. Troubleshooter 1.1

You can follow the below mentioned instructions[1] to uninstall /disable the extensions.

As for the Safe Mode removing the bookmarks, no that doesn't happen. That said, it is always advisable to take a backup of your bookmarks (and your profile in general) [2] so that you are able to restore them from the backup.

1. Disable or remove Add-ons
2. Back up and restore information in Firefox profiles

Finally I went to safe mode and RESET Firefox and deleted all the add-on. Now it is running Ok. I backed up bookmarks even though I don't have to. The RESET does not delete my bookmarks. Thank all guys for the suggestion and help. It is really helpful! Have a wonderful weekend!!!

Appreciate the help. It works well for me.