[SOLVED] Did autoinstall of Word Press 2.9.1 now my site is dead!

While working on my site I saw the notification on the WP dashboard that WP 2.9.1 was available so I did the auto install. I had just looked at my site so I know it was up. Right after the WP 2.9.1 install my site went dead with the message:

"Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@tuneintocancer.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

I switched to two other themes as a test and the site is accessible. With Atahualpa I can reach the dashboard but not my home page http://tuneintocancer.org/blog/ . It seems that either there is a corrupt file or a bug. Any ideas?!