That may be cause Persona was loading user's profile from remote repository.
Did configure Persona and remote repository properly?
Arethere other software are using monitoring file system such as anti-virus, volume monitoring?
You need to isolate the issue and attaching persona log file for problematic user necessary is important to see what was happening.
Don't forget which version you are using.
In case it stuck on that screen, you may need to open support ticket. Support team may require you to take VM snapshot file for further analysis.
