ASPNET_WP.exe problem 80070545 on restart

Hi,

When our IIS/Server is restarted ASP.NET is breaking. The browser is
showing "Server Application Unavailable" and the event log is showing:

"aspnet_wp.exe could not be started. The error code for the failure is
80070545. This error can be caused when the worker process account has
insufficient rights to read the .NET Framework files. Please ensure
that the .NET Framework is correctly installed and that the ACLs on
the installation directory allow access to the configured account. "

We are running IIS 5 on Windows 2000 Server SP2.

I have seen suggestions to run aspnet_regiis -i and then regsvr32
aspnet_isapi.ddl. This worked as a temporary solution, but the
problem is reoccuring.

Any suggestions on how to solve this would be appreciated.

Kindest regards,
Tim Haines.