Users may experience a MySQL error saying that the mybb_sessions table is marked as crashed and should be repaired.
SQL Error: 145 - Table './****/mybb_sessions' is marked as crashed and should be repaired Query: DELETE FROM mybb_sessions WHERE ip='****'
Run the following query in phpMyAdmin. Replace "mybb_" with your table prefix.
REPAIR TABLE `mybb_sessions`
If you want a permanent fix to this problem run this query in phpMyAdmin. Replace "mybb_" with your table prefix.
ALTER TABLE `mybb_sessions` engine = `memory`
Visit this thread for help running MySQL Queries: Common SQL queries and how to run them