Q: Since installing Yosemite 10.10 the Apps Store application on my iMac does not work

installing Yosemite 10.10 the Apps Store application on my iMac does not work properly. Applications show up in the App Store window to be updated but in fact most of them do not download and install. Some 3rd party software does download and install but most Apple and HP Applications do not. They appear in some cases in both the Ready to update or install list and in the "Installed in the last 30 days list". In some cases when I click on "Update" it shows in the "Installed in the Last 30 Days list" but it is not installed.  In the case of the latest Yosemite 10.10.3 beta down load, it momentarily show up like it is downloading but then disappears and does not install.