aspnet_wp.exe worker proces restart issue

We are encounter inconsistant behavior when the server is revooted. Every so
often when the server is revooted the aspnet_wp.exe does not start and until
we have a user request a aspx page we don't know that it is dead.
We get the following error in the event log
aspnet_wp.exe could not be launched because the username and/or password
supplied in the processModel section of the config file are invalid.

What is this saying? We do not edit the mentioned file that we know of what
would cause this?

Thanks