run internet explorer in no extensions mode
from the run menu
iexplore -noext
then go to "tools" "Manage Add-Ons" and remove everything.
that's right, all extensions. get rid of them all.
you'll have to reinstall adobe acrobat and flash but there's precious few others that are necessary to a perfect browsing experience.
On the off-chance that there is, just reinstall them.
That should do it.
Me, I clean up the registry by hand Search for "internet explorer" then all in toolbars (not ie toolbars, you'll know when you see them), extensions, explorer bars, url search hooks, search scopes and a few others, low rights, etc.. You'll have to find all occurrences in the registry, they are doubled up but you should find 6 at least then two more for each extra user. Also from the HKLM-software-microsoft-windows-currentversion-explorer branch, remove all "browser helper objects" and "shell execute hooks"
Do it right and I guarantee you you will not have any pop ups appearing automatically (because they can't)
Don't edit your registry unless you've made a backup and
know how to restore it.
P