I have a Labtec Webcam Pro and use it with Ekiga. I upgraded my system some
days ago and now I noticed that it stopped working correctly.
I see the following error messages in /var/log/messages:
May 23 15:54:13 chrulli
[spca50x_move_data:1611] ISOC data error:  len=0, status=-84
The error messages are repeated over and over again, just the value in the
brackets and the value of "len" changes.
There is a heavy side-effect: khubd eats up the CPU. It is constantly at 100%.
The whole USB subsystem breaks. Nothing works anymore, no USB flash drives,
no printer (connected via USB), etc.
After unplugging the webcam and rebooting everything works fine (just that I
do not have any working webcam now...)