My FIFA 10 game stuffs everytime i try to start a new Season or Manager mode. I can't even reinstall because i'm making a mod.

you prolly messed something up while making your mod.

you will most likely need to reinstall fifa 10.

see this thread & my post in it - http://www.soccergaming.com/forums/showthread.php?t=161482

for a tool that will make it so once you reinstall you wont have this issue reoccuring.