You've checked the song's properties in iTunes e.g. selected/highlighted one of them and done 'get-info' (control-I on a PC) and checked its start and end times ? If they look ok then you could try deleting them from the My Music part of your library and adding them back from your backup of your downloads/library (File > Add To Library) - or do you have them on your iPod or iOS device that you can copy them back from (File > Deices > Transfer Purchases) ? If you don't have them on your backup (or an a device) then after deleting them from My Music see if you can redownload them via the Purchased link under Quick Links on the right-hand side of the iTunes store homepage