I have the same problem on two different machines both running ubuntu 9.04.
Emmanuels excellent suggestion of using "gnomevfs-ls smb://smbserver/mymusic" fixed the problem for me too, but it's localized to rhythmbox as VLC and Movie Player has no problems regardless of whether gnomevfs-ls has been run or not.
I am also certain there is a problem with rhythmbox as calling gstreamer directly as instructed in /usr/share/doc/rhythmbox/README.debian (i.e. gst-launch playbin uri=smb://smbserver/mymusic/musicfile.ogg) plays the music.
I have the same problem on two different machines both running ubuntu 9.04.
Emmanuels excellent suggestion of using "gnomevfs-ls smb://smbserver /mymusic" fixed the problem for me too, but it's localized to rhythmbox as VLC and Movie Player has no problems regardless of whether gnomevfs-ls has been run or not.
I am also certain there is a problem with rhythmbox as calling gstreamer directly as instructed in /usr/share/ doc/rhythmbox/ README. debian (i.e. gst-launch playbin uri=smb: //smbserver/ mymusic/ musicfile. ogg) plays the music.