I guess there is a way to edit reg to disable the homepage from beeing changed, but I havn't tried finding out myself.
But if you want you can use either SpywareBlaster or Spybot Search & Destroy (probably many others too) to lock down the homepage settings. both free and very good.
I used that tactic, but forgot the syntax - it's a matter of adding a
"No..." item (something like NoChangeHomePage) to
HKCU...Policies\Explorer or similar. The value is null or 1.
But if you want you can use either SpywareBlaster or Spybot
Search & Destroy (probably many others too) to lock down the
homepage settings. both free and very good.
Remember, anything that gets registry access (which MS offeres on a
plate to anything and everything, and then adds a few permissions
band-aids plopped on top) can splat the setting.