I am experiencing some login problems.

When I connect to SQL Server 2000 using SQL Server authentication I get error message error 4064, cannot open user default database. I can connect however if I use Windows Authentication.
The problem started when I did the ffg.
-backup sql db1
-restore db1 to another name (db2)
-drop db1
-use sp_detach
-use sp_attach to attach db2 as db1 (rename database)

When I connect in Query Analyzer via SQL Authentication I get the error, however via any other method it works fine.