Just cuz it works, don't mean you can't tweak it!

Restore Registry Defaults:

In Windows XP, there is a great way to restore most registry default keys and values. Whan a new user account is created, the system copies a set of default registry values to the HKEY_USERS hive, and gets those values from the HKEY_USERS.DEFAULT branch.

That's right people, just one branch down in the HKEY_USERS hive could be the answer to your over enthusiastic editing. Exporting values here won't work, since importing would just put them back here. But you can copy individual key values to paste them into a hack that went awry.

The warning about registry changes goes double for this branch. Changes here can screw up all future accounts.