This is definetely a Skype problem. I have the exact same issue with my Microsoft Lifecam VX-3000 which has worked for a year without any problems. I'd say this started with the latest version of Skype 5.8 (my problems began before 5.9 but still exist in 5.9). Will now try the portable solution given here but Skype devs needs to get off their a.. and solve this.
Installing the non-essential updates to Windows 7 fixed this problem on my Win7 Dell Inspiron. The language updates were not installed.