...or better yet NetworkGeezer, lock the computers away so they cant access them :P
but anyway people....
*puts mod hat on*
Please keep on topic...
Sorry if i missed it, but when you say u cant log on locally, and you changed the computer name - is the computer attached to a domain at all?
If so, there lies the problem I'd guess - especially if u have something set in the GP that may suddenly come into affect with this new computer name [if it even allowed it] i.e. a "prevent local log on" type security policy