If you have CIFS mounts (remote mounts) mounted and the remote server goes off-line, there are Linux commands that will hang even when not done on the CIFS mounts. That is why UD has timeouts on all commands. If there weren't time outs, UD would hang. If I remember correctly the worst are 'lsof' and 'df'.
If the remote server is only on at certain times of the day, you shoud unmount the remote shares while it is off.