Here are some symptoms we're familiar with.
When you place an order, as a security precaution you are required to click this button and possibly pass a simple test:
We have found that in some cases even after clicking the button and passing the test you get an error when trying to submit the order. This can happen if there's a long delay between clicking the button and submitting the order. Try the following:
JavaScript is required - please see the Browser Requirements.
One reason the catalog may fail to load in Internet Explorer is that the catalog is loaded in Compatibility View". Try the following:
We are working on new approaches that may improve performance. In the meantime...
We have found the Catalog application performs best with Google Chrome.