The gray screen happening, when there should be a popup, is a browser issue. So far, we have only been able to replicte the problem with Internet Eplorer versions 9 and 10. You just need to use a different browser.
IE 8 works fine, and IE 9 works in compatibility mode, but so far IE 10 doesn't work at all. Internet Eplorer has had issues maintaining compatiility for years, and doesn't work well with many websites including eBay. FireFox or Chrome are free browsers that work much better. You can contact eBay by using one of them.