How do I store this particular, newly bought bottle of aged, red, sweet wine?

[Nicholas_Man]

I bought this from the winery's shop (Achaia Clauss Mavrodaphne Grand Reserve, if you happen to know it). I know that "all wines need to be stored laid on the side" but the lady in the shop told me that this one is an exception and needs to be stored upright. The wine (high in sugars) must not be in contact with the cork because it will cause the cork to dissolve or somehow taint the wine. I'm troubled. I'm almost certain the wine has a regular cork (there is the usual plastic? / foil thing on top covering it so I cannot really be sure). Please reply only if you are an expert. I already know what the generic answer is (store on the side so that oxygen does not get into the bottle...). Thanks.

[C'est moi!]

Grand reserve has already been aged 20 yrs., according to my research. Does it have pine resin added to it, like Retsina? Perhaps that is what the woman at the shop was referring to that could damage the cork? The point of laying the bottle on its side is to keep the cork from drying out and shrinking. High sugar content alone isn't going to hurt the cork. Unless it has pine resin in it, I'd say lay it on its side.