The good news is that my MP3 files are no longer silent - I have replaced Real Player 11 with Real Alternative and it did the trick.

Real Alternative works fine but I might consider installing Real Player 10 at some point in the future because while I agree with Mike Christensen that Real Player is a bit "bloated" I have always been very pleased with the results I get using Real Player to rip CDs - in my opinion it's much better than Windows Media Player, for example.

Anyhow, thanks for the tip. I wonder if there's any chance that future versions of Real Player will happily coexist with Replay A/V?