For anything related to IO (joypad, serial, XE...)
Okay, had a chance to look at my track ball this weekend. Took the opportunity while it was apart to clean the ball and rollers. Anywho, my current belief if the problem is low voltage. Vcc at the MCU is only 4.64V. On the CDX, it's 4.86V. While the datasheet for the MCU says the minimum operating voltage is 4.5V, the chip seems to be designed to go into a low-power standby mode when you reach 4.5V and stay that way to 3.5V. I'm thinking it's right on the edge and popping in and out of standby mode.