What worked for me was down loading the MARMITEC version of AHP. The WARNING is when you unzip and install DO NOT INSTALL TO"ACTIVEHOME PRO" change it to Marmitec or some other name. You do not want to install it over the original AHP. Once you have installed Marmitec, the original AHP will work in window 8.1 If you have a copy of the original AHP just copy it to the Windows or XP program 86 files. You do not have to install, just copy the program. This worked on windows 8.1 and two of my XP machines.