I can't do any Windows Updates, because the latest installer (WindowsInstaller-KB893803-v2-x86.exe) fails to install. An excerpt from the KB893803v2.log is shown at then end of this posting. The problem appears to be that access is denied when attempting to do "DoInstallation:DoRegistryUpdates". I tried downloading the exe file & executing it outside of Windows Update, but it still failed. I tried to do the update in safe mode with the same result. The error code shown on the Windows Update page is 0x80070005. Searching for that error here & elsewhere has not revealed a solution that worked for me. Many of the postings seem to be for different situations which caused the same error #. Does anyone have any ideas / workable solutions for this problem? If it would help, I can also post text from WindowsUpdate.log Thank you. Exceprt from KB893803v2.log follows: 30.390: Registering Uninstall Program for -> KB893803v2, KB893803v2 , 0x0 30.390: LoadFileQueues: UpdSpGetSourceFileLocation for halmacpi.dll failed: 0xe0000102 30.406: System Restore Point set. 30.437: PFE2: Not avoiding Per File Exceptions. 30.469: GetCatVersion: Failed to retrieve version information from C:\WINDOWS\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\Tmp.0.KB893803v2_wxp.cat with error 0x57 30.734: Copied file: C:\WINDOWS\system32\msi.dll 30.781: Copied file: C:\WINDOWS\system32\msiexec.exe 30.890: Copied file: C:\WINDOWS\system32\msihnd.dll 30.984: Copied file: C:\WINDOWS\system32\msimsg.dll 31.047: Copied file: C:\WINDOWS\system32\msisip.dll 31.047: DoInstallation: Installing assemblies with source root path: c:\windows\softwaredistribution\download\ad9c4c2a779933f83b51a49a2c88838d\ 31.047: Num Ticks for Copying files : 672 31.203: DoRegistryUpdates:UpdSpInstallFromInfSection Failed for MSI.Reg.Install: 0x5 31.203: DoInstallation:DoRegistryUpdates failed 31.203: Access is denied. 31.203: KB893803v2 installation did not complete. Select 'OK' to undo the changes that have been made. 31.203: Starting process: C:\WINDOWS\$MSI31Uninstall_KB893803v2$\spuninst\spuninst.exe /~ -q -z 34.609: Software Update Rollback has completed with return code 0xbc2. This rollback requires a reboot. 34.609: KB893803v2 installation did not complete.

Problem solved. After much ado, searching & researching, I found the solution, which was quite easy to fix, once you know what to do. In my case I needed to add a "SYSTEM" group name to my registry in the HKEY_CLASSES_ROOT section (items 6A through 6F in the article at the URL listed below). I am posting the URL containing the solution for the benefit of anyone else who encounters this particular M$ annoyance. http://support.microsoft.com/kb/315353/en-us