Fixed in MySQL 4.0: Avoid using spaces at the end of column names because this can cause unexpected behavior. (Bug#4196)

Fixed in MySQL 4.0.12: You can get a deadlock (hung thread) if you use LOCK TABLE to lock multiple tables and then in the same connection use DROP TABLE to drop one of them while another thread is trying to lock it. (To break the deadlock, you can use KILL to terminate any of the threads involved.)

Fixed in MySQL 4.0.11: SELECT MAX(key_column) FROM t1,t2,t3... where one of the tables are empty doesn't return NULL but instead returns the maximum value for the column.

DELETE FROM heap_table without a WHERE clause doesn't work on a locked HEAP table.