Microsoft has issued a patch of a patch from last Patch Tuesday for Excel, since the fix added some math errors. The fix issued a critical error that would allow for remote code execution and affected all versions of Office from 2000 and up.

In this case, the fix is solid. The problem, as Microsoft spokesman Tim Rains said in a blog posting, is that a calculation error was introduced into Excel 2003 "when a Real Time Data source was used in a user-created Visual Basic for Applications solution (in other words a custom-built VBA function)."

On installing the update, users encountered a 'Real Time Data' error when attempting to use the component with Office's Visual Basic for Applications software.

The patch of the patch is available through Microsoft's Automatic Update.