Some Logitech web-cams have serious problems all of the last kernel revisions (somewhere since 2.6.26 kernel revision). Sometimes when user starts its Linux OS things with web-cam go bad. Symptoms are "Waiting for sound system to respond" when clicking at the sound icon in system tray and ton of "cannot set freq 16000 to ep 0x86" in your /var/log/kern.log. What solves this problem when this occurs is removing snd-usb-audio kernel module from kernel and plugging it back. Cause of this bug is still unknown, and some say it is a bug in some Logitech webcam firmwares which gets triggered by something in Linux boot process. Lets work around it on Debian, Ubuntu and its derivatives...