Problem with mic?

I am running into a problem with the latest Media Recorder release.

My install and setup have not changed since earlier Media Recorder releases, but I am no longer able to record audio with Chrome or Forefox. Works fine with IE.

When I select "audio" in Chrome or Firefox (Windows OS), the popup permission to use mic is displayed. The media recorder widget appears to detect sounds from the mic (bar chart varies), but a message is displayed at the bottom of the media recorder widget stating "problem with mic, check your browser settings". No recording is stored despite the widget indicating that it is "uploading" after the recording is stopped.

Media Recorder works normally on a Mac accessing the same page.