aspnet_wp.exe could not be launched because...

[Guest]

one of our server is registering a log at the event-viewer saying
---- ---- ---- ----
aspnet_wp.exe could not be launched because the username and/or password
supplied in the processModel section of the config file are invalid.
---- ---- ---- ----

it is an unexpected and not justified error because we do not have any
asp.net application running.
i only have installed a windows service built with C#.Net whom send messages
to a socket server

if i have no asp.net application, why i get this error?

the final problem is that, when this error is registered, any .Net
application crash.
specifically any manage code crash


thanks to all