I have Win XP, SP2 and I have a few plugins on Firefox such as "cooliris", "cool previews", "java quick starter" and antivirus plugin. Currently I have installed flash player v10.
In my backup computer (similar software configuration, Firefox without the plugins and less powerful hardware) everything goes fine.
I think that it is some sort of software conflict. I saw in another thread the same problem:
http://forum.freenicetemplates.com/showthread.php?t=43 Author wrote, that it is solved, but when I visit his web, exactly the same pop-up alert appears:
"You have removed copyright notice.Please do not remove design copyright notice. For more informations, visit website : http://www.freenicetemplates.com/"