error message "File Error: Unknown Folder"

I am working with 4 final cut pro 5.0.4 on Macos 10.4.7 and a Xsan with 5.6 Tb but we have aleatori the message "File Error: Unknown Folder" I found an articule in the knpwledge base of apple about and Issue with netinfo and this message but I am working in open directory. The message come every time I try to save the proyect and I need to save as in the local desktop.

Does anybody knows what whappend?

Thanks in advance

G5 Dual core Mac OS X (10.4.7) Final cut 5.0.4