Looking through a Skype forum thread, there appears to be at least 2 issues. First, for Logitech cam users you can try the following:
- Go to Skype / Tools / Options / Video Settings / Webcam settings / Advanced.
The contents of this window will vary depending on the particular model of camera that you have. If there are options for "Low Light Boost" and "Automatic Gain Control", turn them off. Adjust the manual sliders in the window to get reasonable video quality.
This seems to work for some people.
Then there is the more fundamental issue of Skype driver. Here is the link to the thread (
http://forum.skype.com/index.php?showtopic=97038) but the essence is that the older the driver the more likely the issue. Even with the latest driver it is not a guaranteed fix, but many people seem to suggest that downloading the latest drivers works for at least some of the time. Clearly Skype have known about this for a while and are dragging their heels sorting it out.
Hope this helps, T.