Looks like I found the problem. I had my song file saved on a NAS and I was rendering the wav to the same folder on that NAS. When I moved the song to my C: and rendered the wav there also, it finished in about 20 seconds or so. I tried leaving the song on the NAS and rendering the wav to my C:, but that didn't work. Looks like I need to have both song and wav on the local hard drive.

I have a gigabit setup (pc network card, router and NAS all gigabit) - I don't know why it would make 20 second vs 20 minute difference doing it all on the local drive.

Thanks for your help Mac.