PayPal Express 500 Internal Server Error

Hello! I see that there have been several issues with this error over the years, but they were all very specific and don't seem to apply to my case. So here is what I've got... I'm trying to include info that was asked for in other cases..

PayPal Express
NOT GoDaddy Hosting
I have enabled IPN on PayPal

The issue appears when checking submit order on the Checkout Confirmation page and never goes to PayPal for the payment.

Error:

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.

I have the log from PayPal logs but nothing seems wrong, it has all of the order information.

The return URL on PayPal is http://www.charlestonornaments.com/ipn_main_handler.php and that page doesn't show any errors.

Settings in admin
Enable this Payment Module
True

Sort order of display.
0

Payment Zone
--none--

Express Checkout Shortcut Button
Off

Set Order Status
Processing [2]

Set Unpaid Order Status
Pending [1]

Set Refund Order Status
Pending [1]

Express Checkout: Require Confirmed Address
No

Express Checkout: Select Cheapest Shipping Automatically
Yes

Express Checkout: Skip Payment Page
No

Express Checkout: Automatic Account Creation
Yes

Payment Action
Final Sale

Transaction Currency
Only USD

Store (Brand) Name at PayPal
Charleston Ornaments

Allow eCheck?
Instant Only

PayPal Page Style
Primary

API Signature -- Username
USERNAME IS ENTERED

API Signature -- Password

API Signature -- Signature Code

PayPal Mode
PayPal

Live or Sandbox
live

Debug Mode
Log File

Please let me know if there are any suggestions on what to check next. I'm at a complete loss at the moment. I'm in a show today so I'm going to tun off PayPal until I can get back to my computer!

Thanks for taking a look!
Nancy

Guess that I should have said that the return URL is http://www.charlestonornaments.com/index.php?main_page=checkout_process and the IPN return handler is enabled and sent to http://www.charlestonornaments.com/ipn_main_handler.php