Hi Antonio,
I have not heard this previously reported. First, I want to make sure you are on the most current version. Can you please check in Host, Module Definitions and tell me your exact DR version? There is a 40.00.21 patch you can access in Snowcovered.com under Patches and Hotfixes.
If the problem persists with the patch, please see if you can duplicate this on our test site, www.betasprings.com (log in with host / dnnhost ). Just create your own page with Dyn Registration as the parent page. Then let us know your results and your page url here so we can review it further.
Thanks!
Candace