Sometimes when a session is deleted, or no longer available for whatever reason, the link to that session is still shown in the browser (sessions list). When the user clicks the link an error is given, but the session link cannot be deleted.
The conditions for invoking this error vary.
Logged In: YES
user_id=1578174
Originator: YES
Also note that at times the sessions are not listed in order (1, 2, 3, etc).
i.e. During a run of 5 test cases this was the order as displayed in the web manager:
Test Sessions
s0005 kml chinese
s0002 kmz good
s0003 kmz bad
s0004 kml bad
s0001 kml good