About:blank is a CoolWebSearch (CWS) variant, of which there are far too
many. It's an IE homepage hijacker and it bombards you with popups
advertising spyware removal, among other things. Some variants can be a
nightmare to remove once they have infested your system. Unless you have
deliberately set your homepage to display as a blank page, have SpySweeper
remove it and, if it's successful, consider yourself lucky.