I would just like to say that I had heaps of problems after uploading to the latest version 0.7.1 whereby none of my iOS apps would work; Qouch or SABMobile. In General it was set to localhost, I needed to change it to 0.0.0.0 every time I'd do that and restart sab, i'd get a message:
SABnzbd needs a valid host address for its internal web server.
You have specified an invalid address.
Safe values are localhost and 0.0.0.0
Please restart SABnzbd with a proper host address.
Open a Terminal window and type the line (example):
/Applications/SABnzbd.app/Contents/MacOS/SABnzbd --server localhost:8080
Program did not start!
For me the solution was go back to version 0.6.15 where I was able to change it from localhost to 0.0.0.0 and it wouldn't bring up the above message after a restart. This is clearly a bug in the final version of 0.7.1 and needs to be fixed ASAP as I'm sure plenty of people will run into this issue over the next few days.