Windows Logon Process unexpected error

I have one machine that has a problem when it begins to boot: there's a blue

screen that says something like that:

Stop: C000021a Fatal system error

The Windows Logon Process system process terminated unexpectedly with a

status of 0xc0000005 (0x00000000 0x0000000)

The system has been shutdown

There's no virus or spyware (I checked twice) and I don't see anything about

an msgina.dll in the registry.

The only thing that I think that can be the problem is that this machine

once had installed the LogMeIn. I deleted all the references in the

registry but there's not enough.

Any ideas.

Thanks for all your help