WSUS 3.0 - Client not reporting status

Hello,

I have a problem with WSUS 3.0. I am running a Windows Server 2003 (SP2) infrastructure with AD and GP. I recently upgraded to WSUS 3.0 and everything was working fine (all clients appeared in the console and were reporting status).
Yesterday I had to format and reinstall Windows XP Pro (with SP2) on a client computer, add it to the domain etc.
Initially it would not show up in the console, so I stopped Automatic Updates service, deleted the C:\WINDOWS\SoftwareDistribution folder, started AUtomatic Updates service and ran following commands:

wuauclt.exe /resetauthorization
wuauclt.exe /detectnow

After this, the client appeared in the WSUS console, but it would not report status.
I tried several things, but I couldn't make it to report status to WSUS server.
Here's the log of WsusCltDiag.exe:

WSUS Client Diagnostics Tool

Checking Machine State
        Checking for admin rights to run tool . . . . . . . . . PASS
        Automatic Updates Service is running. . . . . . . . . . PASS
        Background Intelligent Transfer Service is not running. PASS
        Wuaueng.dll version 5.4.3790.2180 . . . . . . . . . . . PASS
                This version is SUS 1.0

Checking AU Settings
        AU Option is 4: Scheduled Install . . . . . . . . . . . PASS
                Option is from Policy settings

Checking Proxy Configuration
        Checking for winhttp local machine Proxy settings . . . PASS
                Winhttp local machine access type
                        <Direct Connection>
                Winhttp local machine Proxy. . . . . . . . . .  NONE
                Winhttp local machine ProxyBypass. . . . . . .  NONE
        Checking User IE Proxy settings . . . . . . . . . . . . PASS
                User IE Proxy. . . . . . . . . . . . . . . . .  NONE
                User IE ProxyByPass. . . . . . . . . . . . . .  NONE
                User IE AutoConfig URL Proxy . . . . . . . . .  NONE
                User IE AutoDetect
                AutoDetect not in use

Checking Connection to WSUS/SUS Server
                WUServer = http://leonidas:8530
                WUStatusServer = http://leonidas:8530
        UseWuServer is enabled. . . . . . . . . . . . . . . . . PASS
        Connection to server. . . . . . . . . . . . . . . . . . PASS

WinHttpDownloadFileToMemory(szURLDest, NULL, 0, NULL, NULL, NULL, &downloadBuffe
r) failed with hr=0x80190194

No Error description could be found

Press Enter to Complete

And here's the excerpt from the WindowsUpdate.log (note that I've included everything since last logon, not just after running WsusCltDiag):

2007-05-31      14:19:00+0200      1980      4e4      Service Main starts
2007-05-31      14:19:00+0200      1980      4e4      Using BatchFlushAge = 33455.
2007-05-31      14:19:00+0200      1980      4e4      Using SamplingValue = 471.
2007-05-31      14:19:00+0200      1980      4e4      Successfully loaded event namespace dictionary.
2007-05-31      14:19:00+0200      1980      4e4      Successfully loaded client event namespace descriptor.
2007-05-31      14:19:13+0200      1980      4e4      Successfully initialized local event logger. Events will be logged at C:\WINDOWS\SoftwareDistribution\ReportingEvents.log.
2007-05-31      14:19:13+0200      1980      4e4      Successfully initialized NT event logger.
2007-05-31      14:19:13+0200      1980      4e4      Successfully initialized event uploader 0.
2007-05-31      14:19:13+0200      1980      4e4      Successfully initialized event uploader 1.
2007-05-31      14:19:13+0200      1980      4e4      WU client with version 5.4.3790.2180 successfully initialized
2007-05-31      14:19:13+0200      1980      4e4      Service status is now SERVICE_RUNNING
2007-05-31      14:19:13+0200      1980      248      Successfully opened event cache file at C:\WINDOWS\SoftwareDistribution\EventCache\{785B2FF9-BB35-4351-B443-17E4C2981EE5}.bin for reading.
2007-05-31      14:19:13+0200      1920      778      Trying to make out of proc datastore active
2007-05-31      14:19:14+0200      1920      778      Out of proc datastore is now active
2007-05-31      14:19:14+0200      1980      248      PT: Using serverID {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}
2007-05-31      14:19:14+0200      1980      248      Failed to obtain cached cookie with hr = 80248008.
2007-05-31      14:19:14+0200      1980      248      Failed to upload events with hr = 80248008.
2007-05-31      14:19:26+0200      1980      7c0      Service received logon notification
2007-05-31      14:19:29+0200      1980      7c0      Service received connect notification
2007-05-31      14:19:58+0200      1980      4e4      start delayed initialization of WU client
2007-05-31      14:19:58+0200      1980      4e4      Client Call Recorder finished delayed initialization
2007-05-31      14:19:59+0200      1980      4e4      Setting AU scheduled install time to 2007-06-01 08:00:00
2007-05-31      14:19:59+0200      1980      4e4      AU finished delayed initialization
2007-05-31      14:24:58+0200      1920      778      Out of proc datastore is shutting down
2007-05-31      14:25:00+0200      1920      778      Out of proc datastore is now inactive
2007-05-31      14:29:13+0200      1980      558      Successfully opened event cache file at C:\WINDOWS\SoftwareDistribution\EventCache\{785B2FF9-BB35-4351-B443-17E4C2981EE5}.bin for reading.
2007-05-31      14:29:14+0200      3512       c0      Trying to make out of proc datastore active
2007-05-31      14:29:14+0200      3512       c0      Out of proc datastore is now active
2007-05-31      14:29:14+0200      1980      558      PT: Using serverID {3DA21691-E39D-4DA6-8A4B-B43877BCB1B7}
2007-05-31      14:29:14+0200      1980      558      Failed to obtain cached cookie with hr = 80248008.
2007-05-31      14:29:14+0200      1980      558      Failed to upload events with hr = 80248008.

Any ideas?

Thanks in advance,

NT