I get a very similar bug in Squeeze. I don't get any error messages except "Host is down" on the affected clients (when I try to ls a mounted share). It is consistently triggered by writing across the network to a share on the server. I can trigger it with Picard or Sound Juicer (which both CTD), but it seems to be a random time/write interval before it happens.
Happy to attach any output if someone can tell me what would be helpful. CC -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org