this fix, or a related one also made my USB keyboard work again.

Jan 25 08:56:45 garlique /netbsd: uhub6: Acer Generic USB Hub Keyboard, class 9/
0, rev 1.10/0.01, addr 2 
Jan 25 08:56:45 garlique /netbsd: uhci1: device addr 2 (config 1): can't set sel
f powered configuration

that message came with every kb device plug/unplug, and the keyboard
was dead meat. the problem is gone now.

-George