A little late to the party, but I've had the same problem for a while and stumbled upon a solution/workaround just the other day.
I have two main accounts on my home PC - Administrator, and my own account (with Administrator privileges). Neither are password protected (I know, but it's only me that uses it), and the Administrator account rarely gets used.
While updating to the latest drivers, I discovered that if I log in to the Administrator account, I can open the NVIDIA Control Panel, while opening it in my own account still gives me a DEP error and crash.
My solution (YMMV) was to set up a password on the Administrator account, and run the following from a command prompt:
runas /user:Administrator "C:\Program Files\NVIDIA\Control Panel\nvcplui.exe"
(* note: I'm not at my home PC, so can't check the path - search in the
"\Program Files\NVIDIA" directory for
Enter the password when requested, and the control panel pops up. It seemed to work for me (despite running as another user, changes to the Control Panel made changes to my display).
The reason for setting a password on the Administrator account is that
runas won't let you do this without a password. There is a workaround for that too, but that would lower your security somewhat.