500 AND 404 ERROR.HELP!!!!

Hye…
Ive been using wordpress quite a while. Its works perfectly before this… But now, everythings turn upside down.Its happened since i upgrade my wp from 2.7.0 to 2.7.1

i begin to face bit by bit problem. The latest problem occured when accessing my wordpress page at https://www.mangotouch.com/wp/ , sounds like this….

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

Please contact the server administrator, [email protected] 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.

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Apache/2.0.63 (Unix) mod_ssl/2.0.63 OpenSSL/0.9.7a mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at https://www.mangotouch.com Port 80

Ive been searching for similar problem but still cant find one. i know theres lots of generous and knowledgeable people out there who willing who have generous heart.

PLEASE HELP ME!! My Salary depends on my website!!

Thank You!!