long shot but u never know... Had a similar sounding problem with a Syntek webcam the other day on an SL300 laptop - everything seemed fine except I just got a black screen. After tonnes of lsusb/dmesg...ing I eventually did this and it worked...but doan ask me why
unload the driver module: sudo modprobe -r uvcvideo
Then reload with the correct parameter: sudo modprobe uvcvideo quirks=16
and if that works then make it permanent:
edit the options file (u might have to create one) in: cd /etc/modprobe.d gksudo gedit options
At the bottom (or just add it if empty) add the following line: options uvcvideo quirks=16
and save, reboot and done!