Cannot save any games

The game is playing fine (and did play fine for my first 40 hours or so of play) and I've suddenly lost the ability to save. I press esc to get the menu and when I click on save it just freezes on the menu and does nothing. The same happens when select load game. It feels like its just lost its connection to where games are stored. I have lots of memory and this is a fairly new laptop which runs the game easily in other respects including saving until recently. Restarting steam/ my laptop/ closing all other programs does nothing to help.