Clients not connecting to SMB on OS X 10.6.4. Server

Hi, My OS X 10.6.4. Xserve is serving one sharepoint via SMB. A few clients connect and all goes well. Until sometimes a client wants to connect again and it hangs (PC hangs, Mac Finder stops responding, unable to relaunch). After this happens I see that there are tens of smb connections active, all coming from the same IP address. Clients can still ping the Server but not connect anymore. If I restart the server all goes well for a while again. The logs aren't really helping. The only things I do see in the log (maybe unrelated) are netbios connections from other Macs on the same network. Any help is appreciated.