i played with our trainer just this morning for about 45 minutes with no crashes while testing the ammo funtion. something else must be wrong, in my opinion. i've seen no other posts about our trainer crashing within a minute, etc.
if you have other mods running or any special 'changes' you made to the game then perhaps there is a conflict there.
another idea is to turn off the health option (press it again to hear deactivate) until you need it then turn it on again (while fighting, etc.) and then turn it back off when not needed. perhaps this is your problem on your particular system.