17v voltage spike when rotating mecanum

[chloe]

We're having a very specific bizarre issue:

• When rotating or strafing in auto or teleop with our mecanum drive, we will quickly experience a huge voltage spike and then lose communication and robot code. This means it's not a code error.
• This happens only when our robot touches the ground, not when it's on blocks
• This does not happen when we shake our robot during autonomous or teleop
• This does not happen when driving straight in teleop

We checked the 172.22.11.2 viewer from the browser and there are no sticky errors under the pdp.

Here is the attached log from the driver station.

https://drive.google.com/file/d/0B2J...E3Z3J6Vm8/view

The huge orange block is the disconnect.
If you zoom in, the yellow line (voltage), spikes just before the disconnect:

https://drive.google.com/file/d/0B2J...1nQUYwbFU/view

Has anyone seen this error before?