• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMan\PPP\EAP\25
• HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMan\PPP\EAP\26

Tidy up any other registry keys (eg Juniper) and reboot.

Ensure the following keys are present:

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]
“RunOnceComplete”=dword:00000001
“RunOnceHasShown”=dword:00000001

Or

Group policy [User Configuration\Administrative Templates\Windows Components\Internet Explorer]
Prevent performance of First Run Customize settings - Enabled

Fresh install of XP SP2 immediately updated to SP3 (Also, Office 2007 SP1 installed).

After, both Windows Update and Microsoft Update detect updates but fail to install any.  No error codes or entries in the event logs.  No info in WU Update History (nothing ever installed by this method).

Fix is install Windows Update Agent 3.0.

Save this to desktop then run the following from a .cmd file:

net stop wuauserv

"%userprofile%\Desktop\WindowsUpdateAgent30-x86.exe" /wuforce

regsvr32 "%windir%\system32\wup2.dll"

net start wuauserv

exit

See

http://www.broadbandreports.com/forum/r20453460-XP-Pro-Updates-Fail-after-Fresh-Install-and-XP-SP3-Loaded

Can't install Service Pack (or some/all other updates) directly, from Windows Update or by WSUS.  See http://support.microsoft.com/default.aspx?scid=kb;en-us;822798 for solutions.

This worked for me:

create batch file (catroot2.cmd)

net stop cryptsvc
ren %systemroot%\System32\Catroot2 oldcatroot2
net start cryptsvc
cd %systemroot%\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}
del /Q tmp*.cat
exit

Then delete all tmp*.cat files from %systemroot%\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE} (or add to batch file, as above)

set allowallpaths = trus

set allowremovablemedia = true

set allowwildcards = true

bootcfg /default, /add, /rebuild, /scan, /list

map

expand

fixboot

fixmbr

listsvc

net use [\\ComputerName\ShareName [/user:[DomainName\]UserName] password] | [drive letter:] [/d]

Go to Regedit:

Registry Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion

Data Type: String Value // Value Name: RegisteredOrganization
Data Type: String Value // Value Name: RegisteredOwner

SFC Source change is at same location "SourcePath"

See MSKB 222473