Well it's happened at least five times now so I guess it's yet another collection/collection scanner etc bug.  I'm just posting this here to see if anyone else has this issue.  Basically, if I plug in an external hard disk, basic MP3 player, or even pop in a CD while amarok is running, I lose my entire collection.  Well, when I say lose, if I reboot, it seems to come back without having to rescan.  I'm using SLED 10 with 1.4.3 version of amarok.  Also, my collection is on an NFS share and is large, similar story to everyone else, but wondered if anyone had noticed it.  Will probably log a bug if no one says why I shouldn't.  Oh well, this just proves it can happen to even the best software.  My bet, is it's to do with the ability to move files and have playlists etc know about where they moved to.