Well, I was experiencing identical symptoms to Stephe after upgrading to 0.3.7 (when progressing to next song, not changing and volume too low until hitting volume change), at least while playing ogg files (I don't think mp3s were affected, at least not as severely).
After applying today's 2008 Feature Upgrade youamp no longer works - hangs while 'updating database', and playlist is empty.
Terminal says:
Exception in thread Thread-1:
Traceback (most recent call last):
File "/usr/lib/python2.5/threading.py", line 486, in __bootstrap_inner
File "debian/youamp/usr/lib/python2.5/site-packages/youamp/library.py", line 157, in run
NameError: global name 'sys' is not defined