Vista - Help? Service Failed To Start - no logon for Limited Users

Vista HP - it's done this at least twice now after a restart... (just
downloaded some updates and had to restart)

There's a message (gone now and irretrievable! Aaargh!) in a systray balloon
that said some service failed (?... notification...?) to start, and that as a
result Limited Users would not be able to log on - check the event log...

I did... the only error (ID 10016) listed under System is

The application-specific permission settings do not grant Local Activation
permission for the COM Server application with CLSID
{0C0A3666-30C9-11D0-8F20-00805F2CD064}
to the user XXXXXXXX from address LocalHost (Using LRPC). This security
permission can be modified using the Component Services administrative tool.

Is that what it is talking about??? What does it mean?

How do I fix the (real) error?

MANY thanks in advance - Julian

PS Also checked Services and couldn't see anything that "failed to start"