SSL connection error

Hi there,
We just set up our authorize.net account and I've entered the API stuff. When I go to checkout, it redirects to an HTTPS address:
https://tkdunion.org/store/shopping-cart/shipping/

at which point, I get the following:

SSL connection error.

Unable to make a secure connection to the server. This may be a problem with the server, or it may be requiring a client authentication certificate that you don't have.

More information on this error
Below is the original error message

Error 107 (net::ERR_SSL_PROTOCOL_ERROR): SSL protocol error.

I'm sure this isn't a bug in Marketpress, but can you please give me a clue what I need to do? I tried to generate an SSL key and had 3 options: Private, CRT, and CSR. I don't know anything about this. Do I need a guru for this or am I overlooking something simple?

Thanks for any and all.