[Help!] Analog readings go crazy!

[RufflesRidge]

As others have noted, I would check the wiring carefully for shorts or open circuit. I would also check the roboRIO power light and DS power tab for 5V faults (they may also show up in the DS log, I'm not sure). It may be that metal debris in one of the connectors or inside the roboRIO case or a short on a different sensor is taking down your whole 5V rail which would cause the described symptoms.

[Fletch1373]

I'm a little late here, but wanted to add my 2 cents anyway.

If your potentiameter is a single-turn(i.e. 210 or 360 degree) pot, then look for damage to the device. If it's a 360 model and turns past it's range, it may make contact with the other side and read the opposite value. We had this happen when our arm went too far in testing. It essentially pushed the pot housing apart a little, letting it spin freely. Resetting it to within it's valid range and tightening the housing down again fixes the issue.