This deals with the calendar tab in My CRM.
At the top of the Calendar Screen enter text into the find box and press enter on the keyboard.
The user is then logged out of CRM.
Workaround / Resolution:
This only is happening under the calendar tab, the search field works as expected under the other tabs in My CRM - leads, cases etc.
This issue is currently with development and will be fixed in a future version of Sage CRM.