Thank you for your post.
When you select File -> Import Records -> Bento Data Source..., FileMaker will ask Mac OS X to launch Bento application in the background, and it should then show you the libraries available from Bento. If you are crashing, there may be an issue with your Bento database file. Quit out of FileMaker Pro and perform the following steps:
1. Launch Bento application. Make sure all Libraries are displayed and there is no error message.
2. Quit Bento, as FileMaker Pro cannot import an open Bento database file.
3. Make sure you only have one instance of the Bento application located on your hard disk. Usually with an earlier version, you would get a message that the database was created in a later version of Bento, but there is a remote possibility of a crash.
Relaunch FileMaker Pro, open the file, and try importing the Bento Data Source again. If this still fails, use the Bento 4 to FileMaker Pro Migration Tool. You can find the link via:
Near the bottom of this web page, you'll find the download link "Download Migration Tool".
This utility moves your Bento data into a FileMaker Pro file, where you can then use your original file and import from the migrated file.
Let me know if you continue to run into difficulty.