For some reason since yesterday completely working system can't work without dockstation: screen goes blank, but everything else works.
I still can login as guest and everything will work fine, or switch with ctrl-alt-fsomething to terminal session, but as soon as I start session(with xstart, for example) with my user after appearance of the first icon in the default kubuntu bootloader screen goes blank.
I thought the issue might have been in external monitor, but even if I turn it off in "Displays" and leave only notebook screen it still goes blank after undocking.
The only difference yesterday was replacement of external monitor, but I can't see how this may change anything.
Kubuntu 14.04, Dell - Latitude E6330