Unable to login to admin panel. "Service Temporarily Unavailable"

Hi, I am new to wordpress. I have a jumpline account, and I just installed wordpress 3.0r5 (using the built in installation app).
And I get to my login page with the below link
https://mysitename.com/wordpress/wp-login.php

I am able to login, but it jumps to this error:

Service Temporarily Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Additionally, a 503 Service Temporarily Unavailable error was encountered while trying to use an ErrorDocument to handle the request.

I read thru many posts here, and created .htaccess file with the below code:
SecFilterEngine Off
Then I started getting a different error: (it wont even show the login page).

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 503 Service Temporarily Unavailable error was encountered while trying to use an ErrorDocument to handle the request.

I tried changing permissions, removing the plugins. Nothing works. I am not sure if it is the issue with jumpline, or I am missing something. Please help. Also, let me know if anyone has the wordpress working in jumpline servers. Thank you so much.