click on the link below
http://www.virginmedia.com/
then once the page has loaded click on TOOLS on the main menu at the top of the screen, then click on INTERNET OPTIONS
on the page that comes up make sure it says the same as the above link uder homepage then click on Use Current.in the homepage section towards the top and then click ok.
check this link for more info
http://www.helpwithpcs.com/tipsandtricks/home% 20explorer.htm
You really should take the time to read all the options and prompts when installing things, one of them asked do you want to set your homepage to ask.com, if you'd taken the tick out from next to that option it wouldn't have changed it