The documentation explains this error, though it's not too easy to find: http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html
If you re-create a table that was dropped, it must have a definition that conforms to the foreign key constraints referencing it. It must have the right column names and types, and it must have indexes on the referenced keys, as stated earlier. If these are not satisfied, MySQL returns error number 1005 and refers to error 150 in the error message.