I have Mac OSX users which are being disconnected from SMB shares on Windows 2003 Storage Server.
For some users it doesn't happen, for some users it happens occasionally, for some regularly (up to 10-20 times a day). It is inconsistent. They connect to the share on the server and it will just randomly disconnect them regardless if the connection is currently used or not.
Some Mac users login to OSX via AD, some not - disconnecting happens in both cases. It doesn't happen on the PCs.
I was playing with [Microsoft network server: Amount of idle time required before suspending a session] option and tried to set it up to 0 or 10080 minutes (7 days) but it doesn't help.
I can't use AFP instead of SMB due to its limitations in file/path name length.