Radio recordings coming out as .cap files rather than mp3

A few months back I upgraded to a new Win7 computer and also upgraded from Replay AV7 to Replay AV8. I loved AV7 on my Vista computer and had used it for a few years. I would record radio talk shows using AV7 automatically converting them to mp3 to listen to on my mp3 player. It worked great, for years! But on my new computer it's hit and miss. Rarely does it work! Typically what happens is I get 2 files. One, a very small mp3 file of only a few hundred bits (essentially nothing) and, a separate large (about 80 mb for a 3 hour show) ".cap" file. What can I do with a .cap file? I have verified my settings in AV8, and even removed all my record settings and then reconfigured. The same thing happens again. It seems I sometimes may also get M3U (?) files? Whatever that is. This is very frustrating as I really loved my old set-up. Now, I've spent hundreds upgrading my computer and a whole new Applian package and now I can't get it to work right. What are .cap files and why am I getting those? Any ideas? Thanks.