Check your browser plug-ins and extensions. You may have downloaded something that installed this utility thanks to some fine-print somewhere above a “Yes” button.
It is on your machine. It is some spyware thing.
FR is not running ads.
Sounds like TextEnhance or Google AdWords
http://support.mozilla.org/en-US/questions/887190 for Firefox
http://forums.serif.com/showthread.php?t=115603 for Chrome
Sounds like addware. Maybe FaceTheme?
Check add/remove programs for anything you don’t recognize.
also check for browser help objects
run HiJack-this
One of those browser things, I don’t know why they get turned on and off.
Check out this link, I have a feeling this is what you are suffering from:
http://botcrawl.com/how-to-remove-text-enhance/
Note though, that those instructions may stop this adware from functioning, but you are still probably infected with other viruses/malware that were used to install the adware. That is why, after you managed to get rid of the ads the first time, they came back. So, you should still run multiple scans to get rid of any viruses or rootkits.
I’d suggest downloading MalwareBytes Anti-Malware, like others said, but also get TDSSKiller from Kapersky Labs and a utility called RKill, available at bleepingcomputer.com.
Restart your computer in Safe Mode with Networking Support. Then, run RKill first to stop any malware processes that still manage to run in safe mode. Next, run TDSSKiller to remove any rootkits. Then, run a full MalwareBytes scan and remove anything that it finds. Unless you’ve got a particularly bad virus, that should get the job done.
In case you have to reboot a bunch of times this can save you a lot of time.
MalwareBytes is an essential running program. It has saved my computer quite a few times now.
Who had access to your machine while you were gone?
The only way this could happen would be, malware has been installed into your browser.