WordPress MU

I have a migration related question. Here is what I did:

1. I rSynced all files for WordPress MU installation (version 1.3.3)from one domain (e.g., wwwdev.domain.com/blog/) to another (e.g., wwwprod.domain.com/blog/).

2. I downloaded sql file from database and did a search and replace and changed all places to point to new domain name.
3. I dropped the old database and added the new database.
4. I updated the wp-config.php file on wwwprod server.

When I load the new blog from wwwprod.domain.com/blog, everything looks fine, except that I could not log into the backend using any account. No error msg is given. It simply presents me with the same login form. Could you please help? Thanks so much. --Xiu

can't you change the password with phpmysqladmin if the DB is not too big? its the easiest solution that comes to my mind...