The first bottle of a 2005 Niepoort Vintage Port I opened had a very strong smell of wet cardboard. I am now concerned that the rest of the case may have a problem but do not want to open another bottle to check in case I can return them (waiting to hear from the out of state retailer). Anyone have a similar experience or any suggestions?
cork taint. The rest are probably fine.
Had it on a 1970 Taylor Fladgate. Cork had TCA taint. Other bottles in case were lovely.
Sounds like TCA (cork) taint. I’ve had this 2005 Niepoort VP numerous times, including a 1/2 bottle last week, and can tell you it’s a fantastic VP. It’s also one of Dirk Niepoort’s favorite VP’s he has made so far. I recently re-upped and bought a bunch more 1/2 bottles of this for my “Young house VP” drinking pleasure 
That said, this is a VP that should easily cellar 30-40+ years no problem.
Oh and don’t return the others, I am sure they are just fine. TCA damages a very small percent of all wines/Ports sealed with a natural cork. Just the nature of the beast.