Thanks for the feedback! I will try to your suggestion. However, I still find it rather strange, since I have a brand-new HP Pavillion 15, with 1.7 GHz and 8.00 GB Ram. When I open the same document on a Mac with similar settings, these problems do not occur! Could it be that my HP has some kind of virus causing this problem? I already did a scan but did not find anything. Otherwise this is really not acceptable, and maybe I should switch to Mac forever.