AC to battery causes keyboard/trackpoint to disappear

[tpribors]

Title says it. At some point after some update (either Windows or Lenovo) when I unplug from AC the keyboard and trackpoint goes away. In fact, I think all of USB goes away as I tried to plug in a USB mouse and it wasn't detected, and neither was a scanner.

Has anyone else seen this? It's hard to go backwards now.

[tpribors]

After some experiments it appears that it might be more deadly than just losing USB.

I think the system has totally "hung". Nothing can get it out of it.

I also installed the latest power management driver and utility and it didn't fix it.

Has anyone else seen this?