Hwere's how you can restore full functionality back to a Windows Vista system that's in reduced functionality mode. To do this you need to use Internet Explorer to access the file system (type C:\ into the address bar and hit enter - give this permission in any security prompts). Then navigate to c:\windows\system32\cmd.exe and run this.
However, there's a catch ...
You have to run CMD.EXE as an administrator.
Let's try that again ...
... click "Continue" ...
That command again is: slmgr.vbs -rearm
Finger's crossed ...
It worked!
After a reboot here's what you see.
Clicking "Ask me later" brings back your desktop! Nice!