iMac, Macbook Pro, external drive not playing nice

I have the following setup:

iMac running Snow Leopard, connected to a Time Capsule
External hard drive connected via USB to the iMac

Macbook Pro running Snow Leopard

The iMac and the Macbook can see each other no problem. If I open Finder on the iMac, the sidebar lists my iMac hard drive and the external hard drive under devices. Listed under “Shared” is the Time Capsule and the Macbook.

In Finder on the Macbook, I can see the Time Capsule and the iMac hard drive. I CANNOT see the External drive, which I have set up for sharing.

- I have opened AirPort utilities and verified the External is shared.
- I did a “Get Info” on the External drive and have verified that the shared box is checked.
- I have downloaded and installed SharePoint, and it crashes when I try and add the external drive. Might be a SL compatibility problem.
- I have tried AFS and SMB, same result
- The external drive is formatted as FAT32
- My Windows laptop can’t see the external drive either, however it used to be able to see it. Not sure what has changed.

The Macbook Pro is a new addition. It is for my wife’s use and I’d like for her to be able to store stuff on the external drive. She can use the TC for backup no problem.

Any help with this is greatly appreciated.

Does it behave the same way if you connect the external drive to the time capsule?

Just trying to get an idea if it's config issue on your imac or whether it's the drive at fault.