last weekend we executed a domain rise level to Windows 2003 native and adprep for the forest, domain and gpprep. All logs without problems. But... today all users in the domain are reporting that when they are logged on Windows 7 and Windows server 2008 equipments, if the user tries to map a network share or a printer (both in the same domain) by IP (\\10.10.10.1\share1), they are prompted for credentials, they give the user and password, and they get the error code 0x80070043 - the network name cannot be found. However, if they execute the same test on the same machine but specifying the name of the server(\\server1\share1), they map the share and /or printer without been requeste for a user and password and without any problem. On other hand, if a the same user logs to a Windows server 2003, they can map the shares and printers by name and by IP without problems and without prompting for user and password. Notes: there are the ptr records in the DNS, it is not the problem. Dcdiag and repadmin and logs look ok. Logs from rise level and adprep: all ok without errors.