External Hardrive; can't see data on it

I have a Seagate Freeagent external USB HardDrive with around 65GB of music on it. Earlier today I could go into the drive from my computer and see all the music. Now when I access the drive I only see 1 folder and cannot play the music in it. The data is there because when I right click on the drive and go to the properties it still shows around 65GB of used space. Here is the troubleshooting steps I have tried so far:

Several Reboots
Connected HardDrive to a different computer, same situation (Both computers are Windows XP SP3)
Tried to run CheckDisk but gets to phase 4 and error message is generated stating that windows cannot perform checkdisk.

Please tell me somebody has answer for this. I would hate to think that I have lost all my music.

Thanks in advance for any help or info.