Recently I had noticed that when trying to upload images using the quick link above the post box I would get the thick-box but nothing would show up. I have been beating my head against a wall trying to figure out why and wearing out my keyboard searching. Well I finally got it... If you have antivirus software chances are it has a built in ad blocking feature or in my case I use the ad sweep extension for chrome both of which inject styles into the top of every page rendered in your internet browser to hide known ad sites. I discovered this upon opening the page in developer tools in chrome and deleting the < style > tag at the top of the page at which time my media upload worked perfectly fine. I hope this helps as I have seen quite a few people having issues with chrome and media upload.