\\computer_name is not accessible

Hi have a windows nt4.o server on a network. For some reason I’am not able to access it from the network. When I try to I get the following \\computer_name is not accessible—-Logon failure the user has not been granted the requested logon type at this computer…
In the past I had no problems.
The user rights are okay on the computer. Nothing has changed. No one has access to the computer but me. Any help would be appreciated..