The only cron job I can think of is the indexing done for all files, not just the shared folders.  Thing is it was the same thing happening on Windows, on a drive and folder that wasn't shared.  That would only happen with the 64-bit one, it would quit after a while, usually with the same error as in the title, sometimes with other weird errors.  32-bit would work fine.

I can move the folder to somewhere that is not part of the SMB share just to test it though.