"Service Unavailable" -- but code is not a Web Service

Hi folks,

Getting a perculiar error when I attempt to run an ASPX page. The browser returns "Service Unavailable" when the page is executed. The folder has Integrated Windows Authentication enabled, but by the time the user runs this page they have already supplied password to login etc. Before "Service unavailable" appears, they see the logon box prompt again.

This is output to the event log:

Event Type:      Error
Event Source:      .NET Runtime
Event Category:      None
Event ID:      0
Date:            24/03/2005
Time:            18:00:40
User:            N/A
Computer:      
Description:
The description for Event ID ( 0 ) in Source ( .NET Runtime ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: .NET Runtime version 1.1.4322.2032- Setup Error: Failed to load resources from resource file
Please check your Setup.

In the System Event log, I get:

Event Type:      Error
Event Source:      W3SVC
Event Category:      None
Event ID:      1002
Date:            24/03/2005
Time:            18:00:40
User:            N/A
Computer:      
Description:
Application pool 'DefaultAppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Any ideas folks?

Thanks