I noticed before on my pc laptop that san serif fomatted text was showing up as serif, but thought that was just a compatibility issue… I just looked at auctions I uploaded yesterday on the same computer (iMac) and half of the text matches, the other does not.
I have the description and a measurement/detail block formatted same font, but different sizes. The description is serif now, but the meausurement/detail block is fine.
I had a look at your listing, too.
For the section “Chanel gripoix glass” you specified this font: “HelveticaNeue-Medium”.
This font is included in Mac OS X but it seems it is not included in Windows.
You should only use fonts which are avilable on both Systems or use “fallbacks”.
The easiest for you might be to select the text in question and then select a font from the Font menu or format toolbar in GarageSale.