Bad USB port explanation?

[Engineering]

Hi all.

Hans Petter has been very generous with his time helping me with this, but
I'm now seeing some strange behavior, which maybe someone has seen something
similar or has an opinion

Still having problems running USB webcam on FreeBSD.

Running of Intel D945PLNM board, nVidia 9500GT series video card. Storage is
compact flash, with a CF-IDE adapter. Webcam is no-name Chinese, which is
supposed to conform to UVC spec - no other documentation

The application can display the video and framerate in realtime, and also
reconnect the camera on error.

Only on one USB port is it going haywire. I can disconnect the camera while
the app is running, move it to another port, and it pops up at 30fps. Move
it back to the top left port, and it goes bad again.

>From my point of view (driver and application) there is no difference in
ports - I'm just talking to /dev/ugen

Also - If I plug the cam into a USB2.0 hub, and into the problem port, the
webcam works fine. (?!?)

Power issue? I would call it just a bad port, but then why would it work
with a hub into the port?

We have a couple hundred of these boards in stock, and would like to use
them.

Thanks,
Sam