Submit button not working for all users.

I have received three emails in the past 2 days all describing the exact same problem. The user fills out the form completely, inserts payment info, but when they hit submit, they see a blank screen. They do not go to the thank you page, they do not receive a confirmation email, and their submission is not recorded. Their payment information is also not sent to our merchant site - there is absolutely no record of their submission in JotForm or our merchant site. 

I checked your form and everything in the form itself appears to be functional.  Is the form embedded to a web page somewhere by any chance?  If not, is there anything consistent about those users that you know of?  Web browser or device used would be most helpful.