Freezing up at Checkout

Hi, I am having issues with my eshop freezing up at checkout. Please see attached. It will not allow any new clients to checkout. It was brought to my attention today, but I am not sure how long it has been like this. Any ideas????? Please help, my site is starting to get busy and I can't afford to have this not working.

www.doodler.com.au/shop/checkout

Dear Shakira,
I went to your site to check the checkout page. All working well with me. After I clicking on Continue button, it went to step 2 fast. Please see attached image.
I am not sure how did you check it. Can you please re-check?
Sincerely, Giang

Hello

Daniel my tech guy tested it out on his computer and it works fine as well. *shrug* I am not sure what is causing the problem. I cleared my cache and history thinking it might be that. Still not working. I guess as long as customers can log into their computers it okay.

Thanks for your help.

Shakira

Hi again Shakira,
That is no problem. Please re-test to make sure that it works.
From my side, all works well. If you need any more helps, please don't hesitate to let me know.
Giang