I have just gone to update my game.
I installed the core update 5.81.
I wasn't sure if I needed to apply the March 2013 patch first and then the March 13b second?
Anyway I applied the earlier one first which seemed to install ok but on running the game I get
002: An error has occurred while initializing objects
[ i_opgame:opgame -> i_lines2d:lines2d ]
OK,I fixed it.
Un-installed game and any left-over files.
Re-installed game followed by core update 5.81 and then the mar13b patch.