[nfbcs] popups

[tribble]

Hi all --
over the past few days something has appeared on my system that brings up 
unwanted windows with advertising and other messages. It shows up in the 
task manager and I am able to kill it there, but it doesn't appear in 
add/remove programs so I don't know how to remove it. I ran a virus scan and 
Norton doesn't identify it as malware.
Does anyone know how I can get rid of this thing?
Next time I reboot I am concerned it will be there again.
Thanks.
--le