I use several large external drives with my iMac to manage photos and multiple systems. Lately I've had a frequent problem with Finder crashes. Using Force Quit to "Relaunch" the finder does cause it to quit, but it never restarts.
Trying to restart it from the dock by control clicking the finder icon and selecting "Open" resulted in the error
The application Finder.app can't be opened. -10810
The terminal command
showed several zombie (Finder) processes going. From the blank state of the Desktop, it was obvious none were in working order.
I diligently killed each one after noting its PID using the command:
kill -HUP [pid]
$ kill -HUP 281
$ kill -HUP 27398
$ kill -HUP 27404
Then tried to restart the Finder but found the only way to restart it was with this terminal command:
/System/Library/CoreServices/Finder.app/Contents/MacOS/Finder & disown
It did not really help: it crashed again, soon after. Restarting the machine always fixes it, but that won't help you if you can't isolate the source of the problem.
In my case, I've tentatively located the source to one of the external drives, an old iOmega 1TB drive, although it verifies in Disk Utility. Apparently the "Finder.app can't be opened" error is a very common problem, often related to the use of external drives or Drobos, but sometimes other causes as well. Some people report that Lion clears it up, but that has not been my experience.