Would it also be true on these 3, all or majority of users in User Maintenance have Spawn Task checked?
Usually this setting is very helpful and solves several issues but for myself I've noticed a fairly consistent side effect of Sessions.pvk getting corrupted every X months where X varies by number of users and usage.
I deal with it by scheduling PowerShell scripts to run at night which will stop the service, close all lingering pvxwin32.exe takes, replace Sessions.pvk with a known good small one, then restart the service. Similar steps if App Server runs as desktop application.