http://sn.1w6.org/file/mk-20140922T065617-9wleb6s.html
#phew - another startup error in Synaptic solved: I had forgotten that when release name in sources.list is changed, it MUST also be changed in apt.conf - at least it didn't take me too long to figure it out (maybe there was a fleeting memory left from when I did this before :)) #illlearnthisyet