I am having the weirdest error of all.
Sometimes, when creating or altering tables, I get the \'table already exists\' error. However, DROP TABLE returns \'#1051 - u
This is an old question but I just hit the same issue and an answer in one of the related issues linked at the top was just what I needed and far less drastic than deleting files, tables, shutting down the server etc.
mysqladmin -uxxxxxx -pyyyyy flush-tables