Sometimes computers are such a pain! The last few months something is changing the permissions on my .iceauthority file -- consequently I can't run KDE session. (But I do also have Lubuntu, LXDE and Openbox) Fortunately it's a relatively easy fix (see link below), but there must be more to this problems because every week or two the permissions are changed again and I have to run the fix.
See this Amp at http://amplify.com/u/b401