You may still need to "re-associate" the SQL Login with the DB user.

I've found these two queries to do a bang-up job for finding and fixing orphaned users (and possibly what you're running into:)

--The "new" way. Script to find orphans was pulled from SQLServerCentral.com

--Alter User is the MS recommended method to fix

use [DBName];

SELECT dp.name AS DBUser,

dp.sid AS DBSid

FROM sys.database_principals dp

LEFT OUTER JOIN sys.server_principals sp

ON dp.sid = sp.sid

WHERE sp.sid IS NULL

AND dp.type = 'S' -- SQL_USER

AND dp.principal_id > 4

use [DBName];

alter user /*{User reported from above}*/ with

login = /*{SQL Login for user}*/;

I don't recall where on here I found the "find orphaned users" query, so to whoever posted it, the credit is yours.

What you could try doing to fix your issue is, run the second part of the script, the alter user {whatever} with...

It won't hurt (unless you typo) and it may help.

Jason