See Resolution: Method 1 (preferable) or Method 2 in
http://support.microsoft.com/kb/923100

If no joy, see this related post by my colleague MowGreen:
http://groups.google.com/group/micro...76de7769d04493

How to determine which versions of the .NET Framework are installed and
whether service packs have been applied
http://support.microsoft.com/kb/318785
--
~Robear Dyer (PA Bear)
MS MVP-IE, Mail, Security, Windows Desktop Experience - since 2002
AumHa VSOP & Admin http://aumha.net
DTS-L http://dts-l.net/


Heart wrote:
> This morning I could not open Quicbooks. When I checked the Intuit web
> site,
> They recommended removing and then reinstalling Microsoft .NET Framework
> 2.0
> Service Pack. I have tried to remove Microsoft .NET Framework 2.0 Service
> Pack and reinstall.
>
> During the removal, I got the following message:
> Program has encountered a problem during setup.
> Setup did not complete correctly.
>
> I then checked for updates. The recommended updates were both Framework
> 2.0
> and 3.0. I tried downloading and installing the updates. I got the
> following
> error message:
> Error Code: 0x643
> Try to install the update again, or request help from one of the following
> resources.
>
> For self-help options:
>
> Frequently Asked Questions
> Find Solutions
> Windows Update Newsgroup
>
> I have worked through the first two options with no success. I am now at
> the
> third. Does anyone have a recommendation on what to do next?