I have a similar issue with a few albums in my iTunes library. I got them from a friend and when I imported them to iTunes the time on some songs was much longer than the actual recording. For instance, a 6:30 song might show up as being 17:47 in duration. However, during playback, the song plays at it's normal length. I don't get it. Does the playback for you tracks continue until the 36min mark or do they play for the normal time, eschew the extra 29 minutes, and go onto the next song. If it's the latter (like mine) I wouldn't worry about it. I tried erasing and re-importing but it turned out the same. If it really bothers you I'd try re-ripping and encoding the track, assuming it's from a CD you own.