On one of my SSDs, a Neptune OWC, El Capitan is installed. A very strange thing happened after a security update. All my applications in the folder and the dock disappeared and the computer was extremely slow. When I booted from a different SSD with Yosemite, they were visible. I rebooted with El Capitan as administrator and the applications were back. However, when I log in with my username they are gone. I cloned the Neptune SSD to a harddrive and installed on this disk MacOS Sierra. This solved my problem too. However, some applications are not compatible with Sierra and this system is slower on my MacPro 6c 3,33 GHz, which is eight years old. Can anyone solve this problem for me? I want my applications back in El Capitan when I log in as user, not as administrator. This nasty bug seems to happen often, because my brother experienced it too. Any help is much appreciated. TIA.