Windows update fails with error code 0x643

I have tried almost all of the suggested set of steps in this thread.  Some .NET versions in a sequence will install and then 1 doesn't.  The result is that in each method, something doesn't install.  And it seems to vary.  I also ran into a curious thing when following the Method 1: steps (Manually remove and reinstall .NET Framework), some links would install and download directly and for other versions I used the microsoft update tool - customize - and picked the one I needed and it successfully downloaded and installed that way!

Also, I go to some of these microsoft KBs, like "How to determine which versions of the .NET Framework are installed and whether service packs have been applied" and things don't seem to match up to my PC.  In fact, for that particular KB, only one of the versions listed matched what my system had (2.0.50727.3053).  A couple of them differed only in the last 4 digit segment of the version #.  V 3.0 and 3.5, there was no mscorlib.dll file to even look at!

Also, I think it was also that KB, it said I could take the %system%\Microsoft.NET\Framework, copy and paste it into the Windows Explorer address bar.  Unless it's something that I've never come across, my system doesn't have an address bar in window expl.!  I just ended up using Search, giving it "Microsoft.NET" and let it find it for me.  I realized %system% wasn't the name of a folder, so when WINDOWS folder showed up, I figured that's what it was and that's where I checked all the version folders.

I'm getting completely frustrated and these microsoft sites add to it.

I'm going to try davelasker 's suggestion as my next attempt.  Hopefully that will be the magic bullet.

Sometimes things dont work as expected, in my case sometimes I just wait for the next patch round, or the one after and must of the times a revision or a newer patch is release.

If the patch is not rated as Critical and you other defenses as antivirus and malware removal tools are fully functional and updated then you should be ok... or at least make it without issues till the next round.

In my case I will continue troubleshooting next week, if I find something then I'll be more than glad to share it.

Dan

So, what do I do now that I've removed all .NET packages and 1.1 won't even install?

I tried all suggestions on this thread;  most recently I uninstalled all versions (1.1, 2, 3.5, maybe 3 too) via Add/Remove control panel, rebooted, ran the .NET cleanup tool, rebooted.  Now 1.1 installer fails with an illegal memory write (by the Regsvcs.exe app installed by the 1.1 installer).  Another weird thing is that 1.0 appears to be installed (%WINDOWS%\Microsoft.NET\Framework\v1.0.3705 is present & full of files), but doesn't show up in Add/Remove.

OS is XP Media Center 2002 with SP3.  I can't even remember what the original error was, other than that one of the Oct. 14 .NET updates failed.

Earlier than I was expecting!

Dan

This doesn't work on Vista.  I get a file not found at step 5 and the files cannot be renamed (Access is Denied).  I am running cmd as Admin.  What a huge waste of my time.