if you are getting random popups for your IE like I do, you should start to be very cautious about spywares. they are EVERYWHERE!!
i found this site that teaches you how to block spyware cookies etc.
but i do it a bit differently. instead of blocking all those cookies, i allow only cookies from the domains i know such as regretless.org, regretless.com, pure-essence.net
to do this, (for IE 6)
go to tools -> internet options -> privacy -> click on “advanced” button
and i made my setting like this. I blocked all cookies except session cookies. Then type the domains you wish to allow cookies below. This gives you tons of control about your cookies
you may do similiar things for other browser.
also this site gives you links to many free spyware prevention, removal softwares.