If you’ve ever been plagued by an error 1033 issue in MySQL (replication will show it as well), then I might be able to help you out. The error reads something like, “Incorrect information in file: ‘./mydb/table.frm’. I classify this as another one of MySQLs cryptic error messages. Here is how I determined that this was my problem.
Googling around got me an answer, but I had to read a bunch of different responses to piece together the answer. Essentially this issue (in my case) was a result of the InnoDB engine not loading up when MySQL was restarted. Therefore when MySQL tried to read the frm file (table description) which was written for an InnoDB table with the MyISAM reader, it didn’t like it. Since MyISAM is the fallback engine, it went to that and the table became unusable.