I have been having the same issue since last night. This morning, when I attempted, I got this message....Some residents may have difficulty finalizing their purchases using the Inworld web browser. If you are having problems, please try an up to date external browser. See the status blog for more info.
The blog essentially says for IE, you must be on Windows 7 (I am) and a verision of IE above 7.0 (I am), and for Firefox 28 or later (I am) and for Chrome 22 or later (I am).
The blog refers to this issue as RESOLVED ......however, although I meet all of the browser and operating system requirements they have listed for a fix .......I still cannot access my shopping cart and check out.