If you want to lock your home page so that it cant be change follow these steps
1. Open Regedit (start -> run -> regedit).
2. You'll need to update this in two locations.
HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Internet Explorer\Control Panel
In both of the locations you'll need to add:
Now, if you go and right click "internet explorer" and choose "properties" you'll see that you cannot edit (or change) your homepage. To re-enable that you'd change the dword above to: 00000000
Note:: Changing registry values can be damaging to your PC if you do it incorrectly.