ptl file extensions after backing up on go flex external drive

I have recently purchased a new computer with Windows 8 operating system. I tried to move my iTunes Library from my old computer with Windows XP to an external hard drive (Seagate GoFlex) and then to the new computer. Over three hundred songs of the over 3300 in my iTunes library on the new computer after the move have an exclaimation mark meaning the path cannot be found. When I researched these files in my iTunes Media Folder, I found they had a ptl file extension. I've been trying to work with Seagate and they have said because the location of the files on the old computer resulted in a path name that was too long when backing up to the external drive and that the drive shortened the name and put the ptl extension at the end making them impossible for iTunes to access. Does anyone have any suggestions about what to do to rectify this problem? I can't seem to find any answers from Apple for step by step solutions.