When a user tries to Register on the site with IE browser, they get stuck with the progress bar after they click on Next on the first page. This does not happen on Chrome or FireFox browsers.
I wonder if it is happening because of the Login With Facebook button that appears near the progress bar?
Try removing the Login with Facebook button from that registration view/template and test again. Not sure how that button would be interfering, but that's the best way to find out. We really don't alter the normal JomSocial registration process in any way, so it shouldn't be the problem.
Let us know how that goes,