If your registration is complete , after filling up 'registraion form' followed by email, and SMS. then you can only wait for IR severs to regain 'balnce' which is hung due to rush.
I have got registered in early morning time. And then I was happy to look all around the site. but to my dismay, after an hour, I faced similar troubles, and message like 'your session expired'. At one stage I got just 'loading loading and waiting' only.
So retry your logging in if you are registered in 'non-peak' time.