my hd a4tech webcam sometimes work sometimes not

[shaggytwodope]

By updating, did you just simply run updates? And did you notice if there was a kernel update?

A little bit more info can be useful here to figure out whats going on.

Unplug the webcam, close any running programs that may be trying to access it. Open a terminal and type dmesg. Ignore any data currently displayed, now plug in the webcam and look at the output of dmesg. If you can upload and share all the output you see after pluging in the webcam someone can try to help you further.