Does http://fla15.maxexp.com/tag1.html pops up all the time on your screen when you hit a link on a site in Mozilla, Chrome or Internet Explorer? It is not just an advertisement, it is a virus.
Wanna Know how to fix it? It is easy, you only need to search the file name adTag1.htm wherever it is and delete it.
To make you easier to find the file, you could use This software, download it HERE
Hope fully it useful Smadav