I've seen something along related lines, but with version 7.2. I posted the problem once a few weeks ago, but didn't get any response. Basically what happens in my case is, when I try to change the file format of a radio station (from RealAudio to WMA for example), the station completely disappears off my station list, and I have to totally re-create the station entry (which gets very frustrating after you've had to do that several times). I work with quite a few programs that use Internet radio, and MJ7 is the only one that seems to have a problem even remotely close to this. I wish I had an answer. This problem alone has caused me to switch from MJ to another program just to listen to my Internet radio stations.
Not exactly the problem you're having, but along similar lines. I'm not sure if this will help you at all, except to know that you're not alone when it comes to disappearing stuff in MJ.
Meghyn