Try removing the Skype extensions from Firefox.

http://forums.mozillazine.org/viewtopic.php?f=38&t=1368545&start=0

Edit: You can fix it by updating Public Fox to the 1.0.8 version via Tools > Add-ons > Extensions > Find Updates.

Sounds like a problem with the Public Fox extension: https://addons.mozilla.org/en-US/firefox/addon/3911/

I see the same error in a profile with that extension. Looks like it is caused by the latest update, so try the previous version.

See https://addons.mozilla.org/en-US/firefox/addon/3911/reviews/

by Igor Rashnitsov (Developer) on October 25, 2010 # Submitted fix for review, should be out soon. Thanks for reporting this.

updating public fox from 1.07 to 1.08 fixed the dlwatch (200) error.

Thank You

You're welcome