I just went through a bout of WordPress hell.
I went to check on my blog and I was getting a ton of error messages that meant my db_user account had passed its limit of 50,000 transactions. Now, I can't see this happening as I only get about 2,000 hits a day tops.
Once I fixed that problem I was still getting a few error messages and then WordPress locked me out claiming I did not have permission to be in the admin area of my blog!
I did a bunch of checks and repairs on my tables until I reached the "fuck it" point and started doing drop/create queries for the user tables. Since the contents of those tables do not change often I had no problem restoring them from last nights backup.
Now I'm back up and running but tired... very tired.