I don't hear anything playing, or it's only playing ads.
You can try a different station; or turn pandora off for a bit. If you have another account, or can create one, it seems to fix the problem most of the time and allows you to skip some more - of course, you will have to make new stations. Basically, prevention is the way to go: try to avoid skipping often, or a lot of station changes. If you get an Ad, DO NOT SKIP IT! Usually, if you listen to the whole ad, you will start getting music again afterwards. If you skip it, expect more silence.
[TOR] I'm being asked for a proxy username/password
The tor developers have decided to make Tor, by default, ask for authentication on its proxy interface in the newer versions, which I just updated the pandora tor bundle to use. Some early patchers got a version with an incorrect configruation file. To fix this error, either download the latest saver2/pandora installer and install over your current install (settings will be saved) or use add/remove components on the saver2 menu to remove and re-install tor. Sorry for the inconvienence.