How come some thumbnails show up as a broken image?

Q: For some reason my computer won’t recognize some thumbnails on some sites I frequent (youtube, etc) instead of a thumbnail, it will be a blank square; On some sites I go on where the thumbnail should be, it will give me a string of text (example. open = SymWinOpen; reimg(this);; window.open = SymTmpWinOpen;” onerror=”reimg(this);” />) does anyone knows what this means, or what I should do to fix this?