Sounds like your trackball is mouse 1 and your spinner is mouse 2, and you're using winXP?
Things to look for:
Make sure you mapped to "dial analog"; and NOT "dial inc/dec" as these are for digital inputs like the keyboard.
Disable joysticks in spinner/TB games.
Try unmapping anything on "dial inc/dec".
With winXP, windows sensitivity shouldn't effect mame (and usually doesn't). Win9x it also shouldn't, but often does; don't know about Vista, but should be like XP.