First, just be sure you have no utilities which has been installed to lock the home page
a. "HijackThis" is a general homepage hijacker, detector, and remover which you may be using, (Config, Main, Below URLs will be . . ).
b. "Spybot Search&Destroy v1.3" has a lock (Tools, IE tweeks, middle box check).
Have HTML doc file as HP setting within Tools-Net Options - have altered and updated doc in the past but now find I am unable to assign a new HP, keeps returning to present one within Net Opts. and on Address Bar - have Google Taskbar running.
Any ideas please !! Cheers GMB