I have a Magento with 8 stores, each with a language.
Up to 2 days ago they worked well 7 shops, minus 1 that did not send emails. Thinking it was that store settings, create a new and disable failing.
Now, i can not complete purchases. When i reach the button "place order", clicking, the clock appears for a few seconds, and then stays on the same screen, without error, no message, no logs, no nothing.
No longer I can do.
Worst of all is that it shows no error screen, or system logs, nor any exception.
I'm desperate with this system.
Have you tried by disabling the "local" modules through the app/etc/local.xml file?
I am sure there is a custom extension that is causing some conflict in the checkout page.
Also, please make sure that the error logs and the developer mode are enabled in your website, in order for the log files to be generated.