Error Message:

Registry Editor could not delete the value. The key currently selected is marked for deletion.

Explanation:

A process has marked this key in the Registry for deletion, but it has not yet been deleted because other processes are using it. It will be deleted when it is no longer in use, along with any subkeys. Therefore you cannot take any action, including deletions, on this key or any of its subkeys at this time.

User Action:

No action is needed.