Yeah, I’ve been contending with Leopard / 10.5.2 since certain external USB drives began crashing Finder endlessly (until they’re yanked and Finder springs back to life). Using the Console app, I traced the issue back to this core error message from com.apple.launchd: com.apple.finder Exited abnormally: Bus error. I happened upon a solution that seems to work, though:

First, with the drive plugged in an Finder crashing, go to System Preferences > Sharing and change your computer name. Then, if Finder doesn’t come up and stay up, go to your Time Machine prefs and turn it off. That did the trick for me. When you’re done, change it back, it should stick and not crash.

I have to say, this is definitely one of the more ridiculous bugs I’ve seen in Leopard.