Just to verify: this is only a problem with: Firefox, Skype, and MSN Messenger Live. ?
If you ignore or move the error everything works OK?
System Restore and uninstalling/reinstalling these programs made no difference?
There are no more details on those Application errors?
Did you install any software with the Web Cam? If so have you tried uninstalling it?
On another tack you could try the following:
As a first response you might want to post a HijackThis log for review by our Pros in that section:
Please follow the instructions
HERE & then post your log in a new thread in the
Spyware, Adware, Viruses and HijackThis Logs section.
(Not in this section please).
Please specify what issues you appear to be experiencing along with your log.