Signed-up on your site and logged in from Switzerland by IE8. Accessing the page from an iPhone (Mobile Safari 3.1.3) is flawless, as well as the explicit link provided - before and after the login.
While trying and by mistake, I entered the site as
www.freepromotips.com - and get redirected to iphone.freepromotips.com, which can not be resolved. So either ensure the additional hostnames are resolveable and served by your web server, or disable the Domain (multisite) support in the MJ global config.
In some areas, there might be double mod_cblogin modules published. As well, the Mobile Version / Standard Version switcher appears twice, with the MJ text in between - customized the mobile_iphone template?
In other words: Can't see this issue on your site....
-Kurt.