Cannot log-in to wordpress

Hello, I would greatly appreciate if someone can help me log-in to my blog http://www.99celcius.com/. Here’s the problem:

On April 14, 2008 I upgraded my blog to WP 2.5, it was previously running on WP 2.0.3. I deleted all my previous WP files keeping only my theme (Mandigo) folder under wp-content. I uploaded the latest release, ran the wp-upgrade.php. The upgrade informed that my DB was old and it would upgrade it, it did that and viola it completed perfectly.

So what’s the problem then? The problem is that I cannot log-in to my blog after the upgrade through wp-login.php, you can check it out. It gives errors. I cannot post, modify, delete or do any thing to my blog!

Thinking the problem could be my theme not being compatible with WP 2.5, I tried that and the page went blank. It did not pick up the default theme. I uploaded the latest version of Mandigo and the blog is back perfect, but I still cannot log-in!