Updates to Acrobat XI will not install under Windows 8.1. Error message is 1603. There are no instructions for Windows 8.1 problems with Acrobat. Tried the Windows 7 methods and got no better result. Any suggestions?

Tried install with almost everything disabled.  Tried install from the Acrobat "find updates" entry.  All methods result in an Error 1603 message.  The computer is running Win 8.1 and I couldn't find anything on the Adobe Web site relating to Win 8 or 8.1.  Rather than delete and reinstall the basic program (which runs fine), does anyone have a suggestion to obtain the updates?

Thanks.