After upgrading to XenApp/XenDesktop 7.9, the studio MMC starts crashing.

Browse to the ISO of XenApp/XenDesktop 7.9, go to - x64  > Desktop Studio.

Uninstall the components in the following order:
DesktopStudio_x64
PVS Powershell SDK x64
PzAppV_Studio_PowershellSnapin_x64

Now, reinstall the components in the following order:
DesktopStudio_x64
PVS Powershell SDK x64
PzAppV_Studio_PowershellSnapin_x64

Problem Cause

This happens due to App-V snap-in not getting updated properly. To resolve this issue, we uninstalled - Studio, PowerShell SDK and App-V and then installed them back. The App-V should be installed last in the sequence.

http://discussions.citrix.com/topic/357548-unable-to-start-citrix-studio-on-76-install-mmc-crashes