This is the reason why I hate iTunes.
It's something to do with id3 data (metadata in mp3 files that has info like title, track # etc).
Download this software called TagScanner
http://www.xdlab.ru/en/download.htm
It's obviously a Russian program but it's fine, doesn't have trojans or spyware and it's a great free program for what it does.
It does various things... I use it a lot to standardise the naming style of all my music tracks by renaming tracks from the metadata info.
But in this instance:
Open program
Click on the Tag Editor tab
Click on the folder icon on the right of Path at the bottom. Find the folder your problematic album is in, and you're taken back to the program.
Select all the tracks in the big window.
Click on Auto in the top right window. I'd select the top option, ID3v1.
Now with the tracks still selected, click on Save at the bottom. This is basically just resaving what info is in your files, but as a certain formatting style.
Try reimporting into iTunes when you've done that. If it doesn't work, go down through the options in Auto and try again.