Many developers for Vista noticed all the new issues with editing and/or deleting registry keys. The new security measures turned the whole registry model to a major pain for developers.
A first step to some would be to check if the key is WRP Protected or not. To do that do the following:
Right click on the key -> Click Permissions -> Full Control would be only for TrustedInstaller (users/groupname tab) then the key is WRP. This means only Trusted Installers get to make changes to the key.
Trusted Installer is a service that hosts code for install, update, and un-install of OS components. The service is trusted by the system to check for all the prerequisites such as package authenticity, signing authority and dependencies before making system changes.