[ubuntu] Audacity problems after attempting to record system audio

Ubuntu 14.04, Radeon graphics and audio, installed audacity, worked fine for playing back .flac , .mp3, etc. Then I decided to try and record audio output. Wanted to use Audacity to slow the tempo in an attempt to lea the score of a given instrumental arrangement. Installed pavucontrol, followed instructions on this post:

Didn't work, now Audacity will not play back anything. I can open an audio file with Audacity, but the sound is jibberish, and Audacity fails to close, have to use "Force Quit". Uninstalled Audacity, installed again, same problem.

But Rythmbox works fine, before and after the attempt.

Any and all suggestions greatly appreciated.