most of the images posted on gamerenders dont work they say user posted image now it could be the hosting thats not working if it is that cant someone delete them cuz it jus sits there waste of space id say jus a suggestion
It can either mean the file is no longer hosted, or your connection to that server timed out. There's no strain on the forum itself here with that, so there's no reason to worry about it or anything.
They are due to the hosting running down or your connection not allowing them to communicate. Its usually really old images that don't work due to them being removed from the hosting site.
To view it without refreshing the page, right click those words and choose "view image" it'll either show the pic, or a message saying the file is no longer hosted,etc.
