I'm having some trouble with warlords battlecy 1.

I've made it to about halfway through the 3rd campaign (path of light) but now whenever I go into the game and click the "select hero" button the game immediately causes an error and has to be closed.

Only way that fixes it is to completely remove that characters saved games folder and even then it still causes an error sometimes and requires an fresh install, this means completely restarting the campaign.

I've move the save folder from the game, managed to create a new hero, moved the folder back into the game then successfully managed to load from there so I could complete the mission (3.5 I think it was) but go no exp and clicking continue just loaded campaign 1 mission 1 (undead patrol). Quitting the mission takes me back to the map to see everything is still locked.

Any advice would be appreciated. Not playing through it all over again for a third time.