Technical issues with Heroes III.

I have a problem. I don't know what to do! Platinum keeps crashing... The game runs normally, but as soon as a battle starts, the game crashes and an error message appears. I have a copy of the game. I launch it, and it works normally, but only for a maximum of 2 days, and then the same thing happens again. I'm at my wit's end, I don't know what's wrong:confused: Please help, maybe someone has encountered this... :smile45:

P.S.: Besides Platinum, I have WoG and TE, and they work normally.