Regularly on my iMac, or on my Mac Air I am entering data or text into a webpage when it ( the webpage) suddenly disappears. Hitting the back or forward button doesn't help. If I go back into the site nothing that I have entered is saved. Happens with different websites. Seems to be a particular problem on MACs as my PC doesn't seem to have this problem ( or at least not with the same regularity). Any ideas? Thanks