There are quite a number of different versions of that and a number of ways to get rid of it depending on which version you have.
About:Buster removes SOME of them. Make sure you follow the directions.
These others will also remove SOME of the variations.
They are all free except for the trojan removers but you can get a 30 trial with them.
Spybot S&D (download, check for updates, read the tutorial and scan often, it also does some blocking)
Ad-Aware SE (a scanner, download, check for updates, read the directions and scan.
cwshredder (stand alone unit)(another small scanner for certain things, ALL other windows should be closed)
Download anti-trojan (any of the following)
The Cleaner Pro 30 days trial - http://www.moosoft.com
TrojanHunter - http://www.misec.net/ (trial)
how do i get rid of "about blank" thanks