Okay…

1.) Do you guys have JAVA installed?

2.) Which browser do you use?

3.) Are there other scripts on your website

4.) Do you have a popupblocking content on your PC?

[EDIT]

Gotcha! I found the problem..

Your chatroom name:

<input type="hidden" name="chan" value="Langmangboy[RP]">

Has to be changed! The [ and ] are illegal carracters and can’t be read by the script!

You have to delete them

[/EDIT]