Couple of errors

[Chaos-uk]

Hi all, every time a player logs in to the server I get this error
message, anyone know what it is and how to fix it?

Login: HumDinger
Failed to load 'NULL': Can't resolve package name
Failed to load 'Class None.': Can't resolve package name
Unknown security class [] -- System is no secure.

One other thing, my Webadmin stops working every so often and wont work
again until I restart it, and also the server stops responding to
gamespy etc. but the server plays ok... I can join it etc and it will be
fine.

Thanks