I bought a bottle of Casa Lapostolle Sauvignon Blanc on sale to try. I served it to my parents and we all liked it a lot, especially for the sale price. I went back and bought two cases, one for me and one for my mom. I have opened two bottles from my case and found them to be very disappointing, with an unpleasant off-taste . . . possibly spoiled? I have had the bottles in my basement for just a few weeks, stored the same as all my other wines. When I bought the wine, I left it in the car overnight. It was cold but not freezing . . . could that have caused a problem? I'm sure the store will not accept an exchange (will they?). I feel foolish, but I'm thinking about buying another single bottle and tasting it to see if there really is something wrong with my case or if my taste buds are just messed up. What do you think?

Since I did not taste the wine with you, I can't be sure of the problem. From your description, the most likely culprit is that the wine was "corked," meaning that a tainted cork has imparted a harmless but unpleasant musty flavor to the wine. Since cork taint is estimated to afflict 5 to 10 percent of wines, it's not that improbable that two bottles in a single case could be affected.

I can tell you in all certainty that nothing you did could have caused off-flavors. As long as the wine did not freeze, the worst effect of a night in a cold car would be the precipitation of tartrate crystals. Though sometimes mistaken for powdered glass, these tiny crystals are harmless and tasteless.

Even freezing is not fatal unless it pushes the corks out, which would admit air, turning the wine brownish and oxidized. But this does not appear to be the case here.

Most merchants will exchange unopened bottles if returned within a reasonable period after purchase. Since nothing you did appears to have damaged the wine, you should feel free to exchange the remainder of your case for something you like better. However, because return policies differ, it's best to check with the store first.