I see 2 possible explanations for your issue, as further detailed below. Consider checking both of them to see if either one of them apply in this case.
Cookie problem
It is possibly an issue with a cookie. So try the same scenario usiing another browser. If with that browser the problem does not occur, then it is probably a cookie problem. In that case, just delete the session cookie in the browser where the problem occurs. Then check if the issue is resolved.
Site may be hacked
Since the version of this Drupal site is 7.32, it might simply be that your site was hacked. Refer to SA-CORE-2014-005 (posted a week before this question was asked ...) for some more details.
For way more details about that, and possible approaches to do more research on that, refer to Drupal SA-CORE-2014-005 - How to tell if my server / sites were compromised?Drupal SA-CORE-2014-005 - How to tell if my server / sites were compromised?, which also suggests to use the Drupalgeddon module.