cant connect to sql2000 db. login failed for user - this is a new domain install upgrade from workgroup

We just moved our sql 2000 database to a new server, new instance of sql and migrated from a workgroup to a domain.  I went into the workstation, xp-pro, and in admistrative tools, data sources, and changed the database location to the new instance of sql. the connectivity test there succeeded (but not on antoher machine for reasons i dont understand).  now, when in crystal reports, trying to access the databse (the database is fine, working and accessed by everyone on the timematters system we use) I get the following: Logon failed.  Details ado error code :0x80040e4d Source: Microsoft OLE DB Provider for sql server Description Login Failed for user “tm7user” sql state : 42000  Native Error: 18456 (database vendor code: 18456)   What can i check to fix this?  the new sql instance is the default, local instance and all users are domain users in the new domain.
thanks, experts