Oh, might be an outdated skype. I had to go use beta versions due to the fact that whenever I call/send/receive a message, it crashed.

Ahh, ye I think I have the latest version, but I will reinstall both tomorrow and see if it makes a difference. It must be something in the settings, or a bug/virus like you suggested, specific to my client/computer seeing as no one else seems to have the same problem.

Just tried uninstalling and reinstalling both of them, however Skype still crashes randomly when Mumble is open. Untill I can find a more permanent fix I am using Mumble for the iphone at the moment if I want to use both at the same time!