Got white page after login with link from registration form.

Hi,

Sorry for posting a problem again, maybe I'm just a bit unlucky.
I was testing my site and try to make a new subscription from registration page, when i should fill in information i choose the link already have an account, type in user details and push login button, then i got a white page.
I try to change the url but all site i try to see is white.
Im using firefox, there is no problem with seeing the page on chrome and safari, both works fine.
I try to use debug mode, but only get a message about:
Deprecated: Assigning the return value of new by reference is deprecated in /home/xxxxxx/public_html/wp-content/plugins/ad-sharing/ad-sharing.php on line 44 Deprecated: Assigning the return value of new by reference is deprecated in /home/xxxxxx/public_html/wp-content/plugins/ad-sharing/ad-sharing.php on line 685

Which i think not is the problem.

Have anybody seen this kind of problem before?