Who did you get an email from? That sounds a bit suspicious to me.

Try updating Flash in Firefox's Safe Mode. That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Can you get the installer?

I also suggest some supplemental malware scans. This article lists tools other Firefox users have found helpful: Troubleshoot Firefox issues caused by malware.

By the way, the "Updated Ad Blocker for Firefox 11+" is obsolete and you should remove that extension. You can replace it with the much more widely used Adblock Plus if you want an ad blocker.

To remove an extension, open the Add-ons page. Either:

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

In the left column, click Extensions. Then you should be able to find it listed alphabetically. Some of your other extensions look a bit doubtful to me, so I suggest disabling any that you don't envision using in the next 24 hours.

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

To install Adblock Plus: https://addons.mozilla.org/firefox/addon/adblock-plus/