marketpress ssl admin area...

Hey guys, I've had an interesting development...whenever I start a blog or site I feel has long-term potential I like to secure the wordpress admin area with ssl just in case since I know that after the site reaches a certain size and popularity, it becomes a target for hackers.

However when I ssl the admin area on my current site running marketpress, the "Add to Cart" button doesn't work. This is the error I'm getting...
Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; HPDTDF; .NET4.0C)
Timestamp: Mon, 18 Jul 2011 19:41:03 UTC

Message: Access is denied.

Line: 138
Char: 355
Code: 0

Any ideas on this topic would be helpful...Thanks in advance!

PS: Oh yes..I checked with my hosting and they say the SSL is properly installed on the server