Hi! Thanks for posting.
Normally, ports giving intermittent values is indicative of a short - I'm not certain since it sounds like more than one rio is doing this? - still would be good to closely (under a flashlight or other bright light) inspect the rios for any shavings around the pins. Since it's more than one rio - you may want to work through the electrical system checking for any shorts to the robot frame or other metal parts.
For that matter - does this behavior exhibit when the rio's are powered but not connected to the robot? (like if you connect them only to power on a bench top test system?)
