In reply to Andrew Gadsby.

Further to my previous note in this space. Extensive customer testing has shown that only changing DirectoryCacheLifetime to 0 reduces the issue BUT to solve the problem completely these THREE registry values must be set to zero:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Lanmanworkstation\Parameters
1. DirectoryCacheLifetime to ZERO.
2. FileNotFoundCacheLifetime to ZERO.
3. FileInfoCacheLifetime to ZERO.

See https://technet.microsoft.com/en-us/library/ff686200%28v=ws.10%29.aspx for full details on this matter.