I have one strange problem. I do not know where to look for problem solution. In Resources options in ACP, I have allowed rar extension, but if I want to upload resource that is rar-ed, i can not see that file in firefox new window (when you click on upload your resource), but I can see rar file when I try that from Chrome or IE. More strange is that firefox recognize rar file if I upload attachment in post. So, it is not Xenforo permision i think, it is firefox permission, but I do not know where to look more.