Interactive Logon initialization error

Stuck at a screen for Windows Vista, with following error interactive logon
process initialization has failed , it recommends searching event log, my
clients laptop came with the appropiate software but for some reason, client
can locate them, i dont have copy fo windows vista home premium lying around,
was wondering if anyone encountered this error and of course what is the
solution, already tried the safe mode options, and cant past that that error,
already tried last known good config, and all the possiblities for the
startup troubleshooting, any insight to this error would be greatly
appreciated.

Thanks