I assume that you work within domain.
In this situation the problem could be caused by duplicated value SPN (ServicePrincipalName) assigned to to two different user accounts or assigned both to computer account and domain user account.
You need to use ADSI Edit on a domain controller to find ALL
values in SPN like MSSQLSvc/databaseserver.your.domain.com
and leave only one assigned to a user account on which MSSQLSERVER service is started.
After this change you need to restart mssqlserver service.
The another possibility to solve this error is to configure a tcp/ip alias for a specific database server via utility 'cliconfg'.
Regards,
Yenidai