Tested with rhythmbox 0.11.6svn20081008-0ubuntu4.1 from intrepid-updates, and immediately reproduced the problem again with xfade on (rhythmbox froze).
Tested with rhythmbox 0.11.6svn20081008-0ubuntu4.2 from intrepid-proposed, and I can successfully navigate a song without any freezing or other negative effects (tested over 100 navigations). Crossfade only applies on song changes, not within a song when navigating. It also takes a second to start playing the newly navigated position (compared to instantly without xfade), but this is a very minor problem compared to the freezing bug which has now been fixed.
verification-done
Tested with rhythmbox 0.11.6svn200810 08-0ubuntu4. 1 from intrepid-updates, and immediately reproduced the problem again with xfade on (rhythmbox froze).
Tested with rhythmbox 0.11.6svn200810 08-0ubuntu4. 2 from intrepid-proposed, and I can successfully navigate a song without any freezing or other negative effects (tested over 100 navigations). Crossfade only applies on song changes, not within a song when navigating. It also takes a second to start playing the newly navigated position (compared to instantly without xfade), but this is a very minor problem compared to the freezing bug which has now been fixed.