I would look in mysql error logs for a detail of the problem.
I would think offhand from my experience that it is related to the user table and the addition of the birthday field. You need to use phpmyadmin and check out the table. You can open up the altertable file and may have to manually add the user table query
ALTER TABLE w3t_Users
ADD U_Birthday VARCHAR(10) NOT NULL DEFAULT '0',
ADD U_ShowBday INT(1) NOT NULL DEFAULT '0',
ADD U_TimeFormat VARCHAR(6),
ADD U_Ignored TEXT,
ADD U_OC_Userid VARCHAR(64),
ADD INDEX birthday_ndx (U_Birthday,U_ShowBday)
Now if the above query does not run try running
ALTER TABLE w3t_Users
ADD U_ShowBday INT(1) NOT NULL DEFAULT '0',
ADD U_TimeFormat VARCHAR(6),
ADD U_Ignored TEXT,
ADD U_OC_Userid VARCHAR(64),
ADD INDEX birthday_ndx (U_Birthday,U_ShowBday)
At least thats what I remember when I upgraded a clean a few clean installs but all that had the birthday hack.
