I have my music on my server, which I access via SFTP, I can get to the
files fine but as my music is playing certain files (always different
files) randomly get listed as missing by Rhythmbox. The sever is Ubuntu
Hardy Server, all latest updates.

I can't figure out what is causing this, if I close and restart, the
files are back listed as being available and other files get listed as
missing.

I'm on Ubuntu Desktop Hardy with all the latest updates.