I've had this exact same problem.
I had 1.2 working for a week or two.
All of a sudden, none of my saves were in the load selection. Then, i couldn't re-open the save selection menu.
I went into the KSP saves file folder, my saves were all there.
I though a mod did something.
I deleted ALL local game content (except my saves), did a re-install, no mods, created a game, saved it, quit and restarted, not there, same menu bug.
Obviously not a problem with mods, as the second time there were none.
This needs to be patched real soon.