So you want to check who posted on a thread. Go to the replies column and click on number of replies.

The list with the users who posted pops up. Now you go to click on the number of posts next to a user name to have a look at his/her posts. You immediately get a message that you cannot make two searches within xx number of seconds and have to wait xx seconds. The window disappears again. So you have to click on the reply column again ... and don't click on a user name for some length of time. Which is definitely longer than just 15 seconds.

This bug has been around for quite while now.