I have a few machines that manage to say updates are ready but as soon as you install they all say failed.
Part of windowsupdate.log file is:
WARNING: GetFileLocations failure, error = 0x8024400D, soap client error = 7, soap error code = 300, HTTP status code = 200
2009-02-18 10:29:02:232 1092 a20 PT WARNING: SOAP Fault: 0x00012c
2009-02-18 10:29:02:232 1092 a20 PT WARNING: faultstring:Fault occurred
2009-02-18 10:29:02:232 1092 a20 PT WARNING: ErrorCode:CookieExpired(6)
2009-02-18 10:29:02:232 1092 a20 PT WARNING: Message:(null)
2009-02-18 10:29:02:232 1092 a20 PT WARNING: Method:"http://www.microsoft.com/SoftwareDistribution/Server/ClientWebService/GetFileLocations"
Same error for every update in log
This looks like it describes your problem. Either IIS6 is playing up or the WU client requires re-installing.
Are these Vista / 2008 Machines?
We had something similar (cant remember the exact error code now) which was caused by corrupted downloads of the updates.
I had to download the corrupted updates, unpack them and manually copy the files into the windows\serviceing\packages directory to fix it.
Will probably try re-install of WSUS Client on those machines as there is only 2 - the rest work fine.