Eu recomendaria aumentar o tempo limite do CIFS.
Aqui segue alguns exemplos do Blog da MSDN
Client session timeout It is the most common exchange timeout. This is defined in [MS-CIFS] as a system-wide parameter Client.SessionTimeoutValue. This value can be configured through the SessTimeout registry key [KB102067]. \HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters\ Value type: Dword Value name: SessTimeout Default: 45 seconds (Windows NT) Default: 60 seconds (Windows 2000)
Extended session timeout This optional timeout may be useful in high latency networks. It applies to a timed exchange with a server listed in ServersWithExtendedSessTimeout. \HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters\ Value type: Dword Value name: ExtendedSessTimeout Default: 1000 (seconds) Value type: Multi-string Value name: ServersWithExtendedSessTimeout Default: These were introduced in Windows XP.
Offline file timeout The client uses this optional timeout for a timed operation on an offline file, normally indicated by the FILE_ATTRIBUTE_OFFLINE attribute. This timeout can be configured with the registry parameter \HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters\ Value type: Dword Value name: OffLineFileTimeoutIntervalInSeconds Default: 1000 This was introduced in Windows 2000.