It's not clear from your message, if you are seeing ONLY the default airport, or you are seeing both default and parts of our airport.
If you are seeing default buildings mixed in with the airport and misaligned parkings, the problem is always caused by another AFCAD, coming from another product, which can come with another scenery, but also with an AI Traffic package, like MyTraffic.
Use the free FSX Airport Scanner program to find AFCAD duplicates at KDFW, and remove all the extra, except the default one from MS and the one in the FSDT folder.