All of a sudden, when I try to use Internet Options in the IE Tools
menu, I get the following error message:

This operation has been cancelled due to restrictions in effect on
this computer. Please contact your system administrator

I have no idea why this started to happen and have no idea how to fix
it. My computer is set up as a single user system, and I'm the only
user with an Administrator account.

Any help would be greatly appreciated as I can no longer completely
clear out my cache, cookies, adjust stuff, etc.

This was a problem BEFORE I upgraded w/ the latest XP Service Pack,
which I was hoping would fix it up, but it didn't.