Hello deerfern.
Did you check the link I provided above?
http://support.microsoft.com/?kbid=927978
I recommend reading the entire article to put things into perspective.Known issues with this security update
• Security update 927978 for MSXML 4.0, for MSXML 4.0 SP1, and for MSXML 4.0 SP2 does not support the complete removal of MSXML 4.0 because this version of MSXML is installed in side-by-side mode. To work around this issue, follow these steps:
1. Remove security update 927978 by using the Add or Remove Programs item in Control Panel.
2. Delete the MSXML4.dll file from the %SystemRoot%\System32 folder.
3. Repair the previous installation of MSXML 4.0 by using the Add or Remove Programs item in Control Panel.
The earlier versions of the Msxml4.dll and Msxml4r.dll files are restored to both the side-by-side folder and the %SystemRoot%\System32 folder.
Cheers.