Login Hangs After Sleep, External Firewire Hard Drive


I have an older 2000-era iMac running 10.2.8. I just added a Seagate 200GB external drive with a firewire interface. I've put two partitions on it. The drive itself seems to function normally. Here is the problem scenario:

1. logoff normally with external drive mounted
2. Allow the iMac to go to sleep with the login screen showing.
3. wake up the iMac, then attempt to login (any user)
4. somewhere during Finder startup/load, it hangs with the spinning beachball. It will sit here for hours. The external drive doesn't wake up with the iMac (no spinup sound), but the iMac complains (pops an alert) when I simply power off the drive.
5. The only way out of the hanging login is to poweroff the iMac.

Now - if you allow the iMac to go to sleep while still logged in, it will wake from sleep with no problem. If you logoff, then login as any user (with no sleep), the login is fine. The only failure scenario seems to be logging off with the drive mounted, then allowing the iMac to go to sleep.