will not go to homepage on start

whenever I open my internet the page has changed to "http://files/Internet%20Explorer/iexplore.exe" & its driving me crackers

Hi Carl,
Go into the control panel, then internet options and change the home page to one that doesn't drive you crackers.

Can you please tell me what version of internet explorer are you using.That you can check from the help tab located on the top of the internet explorer(about internet explorer).

If it is less than version 7,try to update it from Microsoft site and one more thing is your Pc is updating or not I mean did you ever saw any pop up like saying updates are ready or some thing like that.

theres a good chance your browser has been hijacked
Either ask for support, or log into the CastleCops forum
http://www.castlecops.com/f67-Hijackthis_Spyware_Viruses_Worms_Trojans_Oh_My.html

First download a copy of HijackThis!2 from http://www.download.com/Trend-Micro-HijackThis/3000-8022_4-10227353.html
Run it and post the results there and follow their instructions
Otherwise time to ask for paid help