wuauclt.exe behind ISA 2000 firewall

Hello

I'm on an Win XPSP2 client in a domain on a SBS2003-box behind an ISA 2000
firewall. No WSUS.
I've used the tips in
http://support.microsoft.com/default...b;en-us;885819
to allow anonymous access to Windows Update and it works fine.
IE is configured to use ProxyServer:8080.

But Automatic Updates still fail with some sort of proxy-failure. Here's the
log.

2006-10-27 12:51:13 3744 b08 Misc =========== Logging initialized (build:
5.8.0.2469, tz: +0200) ===========
2006-10-27 12:51:13 3744 b08 Misc = Process: C:\WINDOWS\system32\wuauclt.exe
2006-10-27 12:51:13 3744 b08 AUClnt Launched Client UI process
2006-10-27 12:51:14 3744 b08 AUClnt FATAL: Failed to get notification
handle, hr=80070057
2006-10-27 12:54:14 1052 99c AU Triggering AU detection through DetectNow API
2006-10-27 12:54:14 1052 e0 AU #############
2006-10-27 12:54:14 1052 e0 AU ## START ## AU: Search for updates
2006-10-27 12:54:14 1052 e0 AU #########
2006-10-27 12:54:14 1052 e0 AU <<## SUBMITTED ## AU: Search for updates
[CallId = {05ED5A03-AEFA-4D21-83BD-50186B917067}]
2006-10-27 12:54:14 1052 140 Agent *************
2006-10-27 12:54:14 1052 140 Agent ** START ** Agent: Finding updates
[CallerId = AutomaticUpdates]
2006-10-27 12:54:14 1052 140 Agent *********
2006-10-27 12:54:26 1052 140 Misc WARNING: WinHttp:
SendRequestToServerForFileInformation failed with 0x80190197
2006-10-27 12:54:26 1052 140 Misc WARNING: WinHttp: ShouldFileBeDownloaded
failed with 0x80190197
2006-10-27 12:54:26 1052 140 Misc WARNING: DownloadFileInternal failed for
http://download.windowsupdate.com/v6...r/wuredir.cab: error
0x80190197
2006-10-27 12:54:27 1052 140 Misc WARNING: WinHttp:
SendRequestToServerForFileInformation failed with 0x80190197
2006-10-27 12:54:27 1052 140 Misc WARNING: WinHttp: ShouldFileBeDownloaded
failed with 0x80190197
2006-10-27 12:54:27 1052 140 Misc WARNING: DownloadFileInternal failed for
http://download.windowsupdate.com/v6...a/wusetup.cab: error 0x80190197
2006-10-27 12:54:27 1052 140 Setup FATAL: IsUpdateRequired failed with error
0x8024401b
2006-10-27 12:54:27 1052 140 Setup WARNING: SelfUpdate: Default Service:
IsUpdateRequired failed: 0x8024401b
2006-10-27 12:54:27 1052 140 Setup WARNING: SelfUpdate: Default Service:
IsUpdateRequired failed, error = 0x8024401B
2006-10-27 12:54:27 1052 140 Agent * WARNING: Skipping scan, self-update
check returned 0x8024401B
2006-10-27 12:54:27 1052 140 Agent * WARNING: Exit code = 0x8024401B
2006-10-27 12:54:27 1052 140 Agent *********
2006-10-27 12:54:27 1052 140 Agent ** END ** Agent: Finding updates
[CallerId = AutomaticUpdates]
2006-10-27 12:54:27 1052 140 Agent *************
2006-10-27 12:54:27 1052 140 Agent WARNING: WU client failed Searching for
update with error 0x8024401b
2006-10-27 12:54:27 1052 140 AU >>## RESUMED ## AU: Search for updates
[CallId = {05ED5A03-AEFA-4D21-83BD-50186B917067}]
2006-10-27 12:54:27 1052 140 AU # WARNING: Search callback failed, result
= 0x8024401B
2006-10-27 12:54:27 1052 140 AU #########
2006-10-27 12:54:27 1052 140 AU ## END ## AU: Search for updates [CallId
= {05ED5A03-AEFA-4D21-83BD-50186B917067}]
2006-10-27 12:54:27 1052 140 AU #############
2006-10-27 12:54:27 1052 140 AU AU setting next detection timeout to
2006-10-27 15:54:27

Any ideas?