According to wine cellar designer Paul Wyatt, "Fortified wines such as Sherry, Port, and Madeira should be stored upright because the high alcohol content will also damage the cork." I've certainly heard conflicting advice on this matter, but my limited experience has supported Paul Wyatt's view. When I've opened aged port (1970 and 1977) that was stored on its side, the cork was amazingly soft, and it crumbled terribly. Same-vintage ports stored upright (at least since I've owned them) faired moderately better. ?