With apologies to Bert, I quote:

Originally Posted by Microsoft
To work around this problem, manually install the security update from the Microsoft Download Center, and then click Ignore when the error message is displayed. To confirm that the installation was successful, verify that the version of the Msxml4.dll file in the %SystemRoot%\System32 folder is 4.20.9870.0.

Detailed instructions and links are here .

John
Internal Medicine