Do a malware check with a few malware scan programs.
You need to use all programs because each detects different malware.
Make sure that you update each program to get the latest version of the database before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
• http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page

See also "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked and What to do when searches take you to the wrong search website

Same here. I'm sure this is a virus or at least traces of one. Doing a clean install of firefox worked. :)

I use a Mac with the latest Firefox and I found out the soclnet issue is coming from Echofon. Disabling the program stops it.

Fortunately, Macs and Firefox doesn't let me download anything unless I give the OK. It's a nice safety feature when you don't know what the heck "c.php" is.

I found this elsewhere.... It may be Echofon....

I disabled Echofon and the messages went away. Thanks for the tip!

I'm a little sad though, because I really liked that add-on (I like seeing the Twitter msgs pop up in the browser). Apparently I need to be more careful of the links I click on in Twitter.

Thanks to Akit and lickskillet for the answer.

The solution works for me, and hopefully it works for others too :)