can’t login / after commenting get sent to blank page

I’m really not sure what version this is. I used the auto install at godaddy on 2/15/09 so I’m guessing it’s the latest version.

The problem is this: When I log in, I get sent back to the login page. No message, no error, no redirect.

I tried commenting on the front end. After doing so I get sent to a blank page.

This is a completely fresh install. No additional plugins.

I did what was recommended here with no effect:
http://codex.wordpress.org/Login_Trouble

Thanks for your help.