Had this problem myself in the past, and still do occasionally, it is infuriating,not a problem for me I can restore my ISP homepage in a few seconds, but what about somebody new to computing,?they boot up log on and find the page with their webmail icons ect gone,and they havent a clue how to deal with it.
The other complaint I have is that it does not appear to be possible to delete these parasite URLs from the homepage box in internet settings, without deleting history ect.