Any saved games after version 4.2.7 is no longer backwards compatible as there are now separate saved games for each map or game (addon) played.
Basically you can now have 1000's of saved games and are all divided and set to each map/addon.
It is therefore to your advantage to delete all saved games and use the latest version of 4.3.2
http://www.proasm.com/files/sw/Swp432.zip
427 - Fixed missed autosaved games
429 - Added save game for each .grp addon
430 - Added saved games for each user map
430 - Modified and forced autosave at runlevel
432 - Fixed loading saved game name in log
432 - Saved game now saves current track and not redbook[level]