Can't install an update, help?

[jguimond]

Microsoft .NET Framework 3.5 SP1 Update for Windows Server 2003 and Windows XP x86 (KB982168)

^^^^

that's the update I've tried to install, even though I did update something that is supposed to make sure it doesn't fail. It still did.... and then the microsoft site I was using to do this gave me a pop up saying: installation failure. Error Code: 0x643
Try to install the update again, or request help from one of the following resources.

any help is appreciated.

[Bull50]

This is the problem related to the Microsoft Installer logging and Windows Update verbose logging. You need to Enable Microsoft Installer logging and Windows Update verbose logging. Just go with the below given instruction for same.

1. Click on Start
2. Click on Run
3. Type Notepad and Hit Enter
4. Type the following commands in Notepad.
   

   Windows Registry Editor Version 5.00
   [HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer]
   "Logging"="voicewarmupx" 
   "Debug"=dword:00000007
   [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Trace]
   "Flags"=dword:00000016
   "Level"=dword:00000004

5. Go to File Menu and Select "Save As"
6. Name it as LoggingOn.reg and Save it on Desktop
7. Go to Desktop and Run the LoggingOn.reg file (This will add registry to Windows Registry)
8. Click on OK if asked for confirmation
9. Install the Update again

[jguimond]

Still not doing it. Guess we'll have to get this pc reformatted.....

[Author]

Still not doing it. Guess we'll have to get this pc reformatted.....

Well, formatting the system is the sure fix of any problem, but that is the very last option. Anyways, before going for the same, i'll suggest you to please go through some of the articles mentioned here regarding the same problem and see if any of it helps you:
Techarena Search.