[SOLVED] WP Admin login problem

When I went to bed last night, the site was working fine. My partner, Judy, was up very late putting the new issue's articles online, and she had terrible problems all night. She was not able to login at the wp-admin page for the longest time. I'm having the same trouble now. What could be causing it? She was able to get in intermittently overnight and managed to get the issue put together.

Just now, I was able to get in via an email about a comment needing approval. Any ideas what I should do? Ah. Just now, I got into Dashboard, after sitting looking at the login screen for about 15 minutes.

In desperation, thinking there was some kind of new plugin glitch, I went in via FTP and deleted the Register-Plus and WP-Captcha Free plugins, although they had been working fine before.