Samsung accessory issue

When I key in my data on Gmail some of the characters do not show up? There is some issue with my keyboard, BUT it is most likely not my Samsung NB Series Keyboard because it only happens with certain sites. I can be happily typing along here, but if I am writing a email from my Gmail account the keys decide to eliminate an entry and some of the characters don't show up. So I constantly have to backspace and re-type. Or then it just freezes up for a few seconds which makes it even worse! This also happens on some of the other sites that I use and enter data. I just don't understand how it can work perfectly on some sites and not on others??