If it's a large file, you're likely hitting the post_max_size limit in PHP. Adjust that so it is greater than or equal to the size of the file being uploaded.
Do you have permission from the original author to upload that particular file to your forum for, presumably, redistribution? http://themeforest.net/item/blackfyre-create-your-own-gaming-community/10618851
I have purchase it No problem. But the another reason is a testupload, that was a random file, normaly i use another files, like images psd files etc.
