If after you've made payment from your account say bank account, credit card etc and after confirmation it redirects you to IRCTC website. But during this time the "waiting ..processing the transaction.." message pages may hang on for some time say 1 minute or more. This can happen sometimes due to network failure.
Click on the image to zoom it:
Sometimes it can be ..redirect.. URL in the address bar. After 1 minute of so just press ONCE F5 or "Refresh" from right click or from Tools. Don't press Enter from the address bar. In my experience in more than 50% of cases it goes through and shows success at IRCTC otherwise your transaction will timeout and your ticket will not be booked. Remember I use Firefox as my primary browser.