We've recently discovered a minor bug in EHS. If you have an activity that has an & (ampersand) in the title, and use EHS to add that to the list of allowed applications in admin mode, upon logging out, EHS complains that it cannot read the settings file (with a message like "could not read admin password").
It looks like the enterprisehomescreen.xml file is written back without properly encoding the ampersand symbol - correcting it in the file to "&" fixes the problem.