Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac Options) key, and then starting Firefox. Is the problem still there?

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Tried starting it in safe mode. It still happens. I'll try the malware checker next.

There seems to be something wrong with the Turnkey website all but one of the links in the malware article links to. I was able to get AdwCleaner but that's the only one since it was the only one not on the apparently defunct website the others were on.

Hmm, most of the links are on completely different servers. For example:

• www.malwarebytes.org
• www.superantispyware.com
• www.microsoft.com
• support.kaspersky.com

If all of those are getting diverted to some other site, you may have a more serious infection. You could try the specialized forums listed in the article in that case.

Okay, I downloaded every anti-malware program you listed and a great deal more of then just those. I ran them all. It hasn't made any difference.

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

FredMcD said

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

I tried that. And yes, the problem is still there in safe mode

Call your ISP and start asking questions.

What has this got to do with my ISP? It doesn't happen in IE, only Firefox which suggests that this is a firefox issue. Also it doesn't happen on any of the other computers in the house. Only my laptop.

It happens with Firefox in Safe Mode. It happens with the computer in Safe Mode. So I am thinking the problem is outside the computer.

Crap. I just hit the wrong button and now this question is marked as solved. How do I show that it is still unsolved?

Go to that response. To its right there is a "not solve" link.

Hmm, it really sounds like a fixup problem, but the prefix preference has its normal value of www?

Sometimes inexplicable problems are caused by corrupted program files. For that we suggestion:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(1) Download a fresh installer for Firefox 42.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox (if applicable).

(3) Rename the program folder as follows:

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(4) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Does a cleanly reinstalled Firefox handle typed URLs normally??

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

jscher2000 said

Does a cleanly reinstalled Firefox handle typed URLs normally??

That seems to have solved the problem! Thanks so much.