The reason why you can't reset your Homepage is because of your Spysweeper and/or zonealarm.
I know both are watching the homepage and try to prevent it being changed.
For your spysweeper, do this:
Click shields (in the menu left)
Click the tab Internet Explorer
There you see: "IE hijack shield" and under it: "Edit IE hijack Shield settings"
Check "Edit IE hijack Shield settings"
This will open some settings below.
There you can change what you want as IE home page shield (your homepage) and click save next to it.
Under it, you will see also Advanced settings where the url http://www.microsoft.com/isapi/redir.dll?p...6.0&ar=home
You can change that if you want, or you can also uncheck
"Automatically Restore Default without Notification".
In case above didn't work, it's your Zonealarm responsible.
For that you have to change your Homepage in Windows safe mode, because shutting down zonealarm and then changing it won't work.
In some cases, Zonealarm stays stubborn here and uninstalling Zonealarm, then reboot, then changing homepage and then reinstalling Zonealarm should do it.
But I guess changing the settings in Spysweeper will already solve your problem.