Gnoman

Solved it yesterday, actually. Turned out to be a known pilot bug in vanilla KSP.

Periodically, in Career mode -I haven't played in the other two modes since the update very long, may not be confined to career-, I have a problem with the entire interface ceasing to work. The Retrieve Vessel and Return To Space Center buttons in flight visibly click but do nothing, and if I alt-F4 to close the game, then reload the save, none of the space center buildings react to the mouse pointer in any way, and the return to menu arrow is unclickable. If I start a new career, it works normally until the same thing happens again. The only common thing between the three times this has happened (which is likely a coincidence) is that in all cases Jeb Kerbal had recently been killed in an accident (I play with reversion disabled). I am running Windows 7 x64, and have the Steam version of KSP (which I believe to be the 32bit version). The only mods I have installed are KAX v2.3.3 for KSP 0.90 StageRecovery 1.5.3 I am unable to take screenshots of the problem, as that functionality also appears to be broken.