Start with Adware, Spybot, Cwshredder and a scan with Housecall.
Read http://www.doxdesk.com/parasite/ to learn more about these things which your antivirus ignores.
Started sometime yesterday. Basically every site that has advertising on it causes an "Enter Network Password" windows dialog box to pop up.
on cnet.com I get an Enter Network Password prompt from "adlog.com.com"
on msn.ca I get one from global.msads.net
on cnn.com it's ad.doubleclick.net
This is driving me crazy. It's worse than pop-up advertising, because it's constant, on every single page load. How do I fix this?