Note that many websites have their own advertising, unrelated to adware.
Possibly related to Context Plus and Apropos Media.
Appears to search through its own hidden cached web pages for keywords typed in Internet Explorer and search boxes. Displays adds based on these keywords.
Some code analysis suggests that it tries to bypass the windows host file by using its own DNS file to resolve IP addresses for displaying adds.
Start computer in safemode. http://www.xblock.com/tt/index.php?x=&mod_id=2&id=132