I just noticed that my shopping cart is not successfully going to the checkout screen or cart after a customer creates a new entry.

All I'm getting is a blank screen, no errors, nothing. If I refresh the screen, I get a red error box stating that the customer record already exists, and I can then continue to check out fine.

Testing with Chrome, but IE just did the same thing.

I see this in the URL at the top:
https://my_web_site.com/index.php?ma...create_account
(fictitious site here)

Anybody know where I can start to debug this?

Thanks.