As a number of you pointed out to me at the end of the week, whenever you tried to log into the site, it just put you back at the home page, or log in screen, but didn't actually log you in.

I had the same problem - which given that most of the site is administered through it's web interface, was incredibly frustrating!

After find a few thread on drupal.org about this type of problem, and following a few fruitless leads, I finally found a post that suggested clearing the sessions table in the Drupal database. So, I went into phpMyAdmin and tried to select that table, which gave me an error: Can't open file: 'sessions.MYI'

So, it appeared something was wrong with the sessions table, this is the table that stores information about each user session when you log in. That seemed to make sense given the situation.

So, I searched on drupal.org for postings about that error message, and found: http://drupal.org/node/25418

It basically said to run a command to repair the table: REPAIR TABLE sessions QUICK;

But, I wasn't really sure where exactly, or how, to run this command. Tried a couple things with phpMyAdmin, and eventually figured it out! Now I'm in and hopefully you are too!

Tim