all a suddent i am getting this error Login failed for user ''. The user is not associated with a trusted SQL Server connection.

<connectionStrings><add name="MyConString"
         connectionString="data source=192.168.0.1;Integrated Security=SSPI;Database=MyDB"
         providerName="System.Data.SqlClient" /></connectionStrings>

above is my connecton string saved in web config file.

i am using sql server 2005 hosted in my office domain controller.(windows server 2003 R2)

i have been using this domain controller to host our intranet. 

for last few years i i have being using this setup without any problem. 

today i keep on getting this error. "The user is not associated with a trusted SQL Server connection."