Ah, okay, I've found this:
»nvidia.custhelp.com/app/answers/ ··· tususer/
Beginning with driver version 188.97 for Optimus notebooks, the driver creates a special Windows user account for security purposes, named UpdatusUser.1 This account is a dedicated and write-restricted user account that runs a service for updating Optimus profiles through the NVIDIA server. The service cannot be run without this account. On Optimus notebooks, this account is created regardless of whether NVIDIA Update is installed. When NVIDIA Update is installed, the additional driver update, application profile and SLI profile update capabilities become available.
No one maybe able to help on this one.--
The only thing necessary for the triumph of evil is for good men to do nothing - Edmund Burke