Why is Audacity hanging after processing noise?

Audacity 2.0.5 on Ubuntu 14.4, installed with Ubuntu rather than compiled.

Audacity is hanging over and over as a process an MP3 of a Skype call. For some parts of the call, the Skype connection was breaking up. When Audacity runs through that part of the audio, it often hangs shortly thereafter; I have to kill it. Sometimes, it hangs even if it didn’t run through a noisy section.

Also, sometimes when I run through a noisy section and then I move the cursor back to replay a section, Skype only outputs quiet static, nothing else. (The static does not resemble Skype bad-call sounds; it is a different phenomenon.) The only way to get beyond that is to restart Skype, and then I hear the audio properly.

What is happening here?

Do you also get the problem when Skype is not running?
Try, logging out of your computer, then back in again - If Skype automatically starts, shut it down, then launch Audacity. Then try processing a file - what happens?

Thank you! Without Skype running in the background, the problem does not occur.

It’s hard to be sure, since the problem was occuring irregularly, but it looks good.