ASPNET Account generates Failed Audit

[Rod Kestler]

After applying the KB Automatic Update #833987 (JPEG
Security Issue), our development server suddenly will not
allow any IIS 6.0 App Pool running with identity set to
ASPNET to run. The Event Viewer shows the following trace
from the Application Log:

Event Type: Warning
Event Source: W3SVC
Event Category: None
Event ID: 1057
Date: 9/15/2004
Time: 3:50:06 PM
User: N/A
Computer: --machine name hidden--
Description:
The identity of application pool 'TestPool' is invalid,
so the World Wide Web Publishing Service can not create a
worker process to serve the application pool. Therefore,
the application pool has been disabled.

And the following Failed Audit in the Security Log:

Logon Failure:
Reason: User not allowed to logon at this
computer
User Name: ASPNET
Domain: --machine name hidden--
Logon Type: 4
Logon Process: Advapi
Authentication Package: Negotiate
Workstation Name: --machine name hidden--
Caller User Name: --SYSTEM ACCOUNT HIDDEN--
Caller Domain: DEPARTMENT
Caller Logon ID: (0x0,0x3E7)
Caller Process ID: 2736
Transited Services: -
Source Network Address: -
Source Port: -

Any clues as to why this would sudden start occuring
would be greatly appreciated. Incidently, our production
server and User Testing servers BOTH auto-updated with
the same Hotfix (833987) and NEITHER machine displays the
same behavior. All 3 machines are running Windows 2003
Server / IIS 6.0. We have temparily band-aided the dev
server by running our app pools under the fixed principal
NETWORK SERVICE.