The specified network name is no longer available

Since a few days a have an access problem on one of my servers in my network. I cant' reach the share drives of that server anymore. Nor by IP then by Name. It is possible to ping the server and connect with other network tools (e.g. VNC). I tried to solve the problem by taking the server out of the domain. As I tried to rejoin the domain, I got the message 'The specified network name is no longer available'. Has anyone a hint what I can do?