If you are using any of the 360 works plugins and the computer has Java 7.25 installed and the OS is Windows, then it will crash exactly the way you say.
If that's the case, you have to remove Java 7.25 and install Java 7.21. That solves the problem.
Thanks so much for the speedy answer!
I was hopeful because the client DID have the 360 Works email plugin installed.
I removed it, and gave it a try, but the same thing happened.
Any other ideas?