Site Configuration returns blank page
I would start by troubleshooting the horrid White Screen of Death.  Once you find the culprit module/file/function/setting this should be much easier to fix.

You may also want to scope out the Language Dropdown bug list, the i10n_update bug list and the i18n bug list.

If you will post back with details regarding the WSoD I'll do my best to update my answer.