On Xubuntu (Oneiric), thinking that I had duplicate songs in my library, I clicked the option to remove a file from my library (I think).  The song was on a network (CIFS/SAMBA) share that was mounted via Gigolo.  Later I discovered that the song, a flac file, was not a dupe, it was completely missing from the library in gmusicb.   Checking out the mountpoint, I found that the song was not there but apparently the OS had renamed the file "0XKYB5~X", so that gmusicb no longer recognized it.   I tried to rename it, but got permission errors - good thing though, b/c  I went to the  'server" machine, and behold, the file was there in its original form and name.  So can I assume that gmusicb told Xubu to rename the file locally?  Is there any way to undo this marking/renaming??

I don't know what could have happen, gmb only rename/write the file in a few cases :
- rename/mass rename/reorganize library
- editing tags, in that case it's either writing in-place if the tag has enough room, or creating a new file with the .TEMP extension, and then replace the old file by the .TEMP file
So I doubt gmb renamed a file "0XKYB5~X". I don't see why the file would have a different name locally than on the server, that looks more like a problem with the server or gigolo.
So you are saying that this file has a different name locally than on the server, even after a restart of gigolo and of the server ? I doubt that is supposed to happen, no matter what gmb or any other software would do.