Cufon Breaks when I add a product to my cart or other tasks which may refresh page

The title says it all really.

An example of the cufon breaking is when I add a product to my cart,

example here http://joemeetsjoy.com/products

When you click buy now then click ok on the pop up box the cufon breaks.

It also happens if you go the the shopping cart and choose a shipping option.

Any ideas why this happens.

Thanks