Hi Jackie,
This really is a mysql question, not a Wordfence question. It looks like you have table corruption that was probably caused by your server suddenly powering off and on again. You need to run a repair on those tables. but please post this question in the mysql forums or on stackoverflow because Wordfence did not cause those tables to get corrupted - it just happens to be our tables that are suffering from the problem with your database.
Regards,
Mark.