Black page after editing..

I just upgraded my wordpress from 2.5.1 I believe, to the latest version of wordpress.

I received this problem before and after the upgrade. I figured that since my wordpress was outdated, that the error was occurring. So, I upgraded my wordpress to the latest version which is 2.9.1.

My Problem:
I logged into “/wp-admin/” but when I go to edit a page, and when its time to click “Update” it redirects to a blank “/wp-admin/page.php” page, and the changes never get made.