On my Windows 7 PC I suddenly had problems to connect to Windows shares (neither shares from other Windows computers nor my ReadyNAS). I always got the message ""System error 67 has occurred. The network name cannot be found" . This did happen even if I tried to connect to the IP address instead of the Netbios name.
The root cause for that issue was a missing entry "LanmanWorkstation" in the network provider registry key:
This key did contained only the values "cbfs4,npnotes" but no longer "LanmanWorkstation". After changing this key to "LanmanWorkstation,cbfs4,npnotes" everything worked fine again.
However, I still have no idea why this entry disappeared...