I see what could cause this since I used integers as several variables, but you haven't provided enough details for me to really be able to narrow anything down.
Does it happen when you open the program? When you log in and it grabs your balance for the first time? Or does it happen when you try to start the autobetter?
I will change the integers to longs to avoid any potential overflow and it should work fine. Will throw up v98 in a tiny bit that will attempt to fix this.
ËDIT: Oh and please add a function to reset to base when reaching maxbet.