Maybe you can have a look at the following links:
https://jira.skype.com/browse/SCL-335
https://jira.skype.com/browse/SCL-482
https://jira.skype.com/browse/SCL-681
http://forum.skype.com/index.php?showtopic=92618
http://forum.skype.com/index.php?showtopic=215021
At least you should find something under ~/.Skype/logs (if this subdirectory is not there, create it before starting skype)
which could tell you some more details. Seems it can also be a workaround to unplug your webcam before starting skype,
but naturally that's only an option if not built-in ...