Acer - Vista Licensing problem

My friend, having problems on his Acer machine, was informed by me to try a system restore and I guided him over the phone to do it. It didnt work and he tried a few times again. Now he cant properly log into his system (he can only get in through safe mode) as he gets the error that the software licensing service is inconsistant with the database ( or something similar). I have the impression it is to do with Vista authentication so I phoned Acer but the not so caring guy said my friend should have used their system repair via the user guide so now he needs to either take this up with MS, buy a new OS or pay £48 to Acer and wait 3 weeks for system restore disks to be sent to him!

I asked on another website if there was any alternative and no one replied to me after 5 days. I found instructions in some thread to reactivate the authentication but when I tried to follow them (it said in system restore their is an authentication tab/button) I hit a dead end.

Please can any you guys help.