Skype Problem

Would anyone know why Skype is crashing my P.C.?
The weird thing is that it is only when I speak to one person. When I speak to anyone else it’s fine.
It just crashes without fail anyway but things that increase the speed with which it happens are browsing and file transfers. Watching a youtube video for example always crashes it although it often makes it to nearly the end of the vid.
It would appear to be a bandwidth issue since increased use increases the chance of crash but I have no problems with torrents and they use a lot more than skype should.

Thanks in advance for any advice. I’m using a wireless modem if that makes any difference. Also could this be anything to do with it?:
http://technology.guardian.co.uk/weekly/story/0,,1747343,00.html

Cheers