While using Netscape-Communicator 4.72 in the Linux Standard 6.2
distribution, the following
occurs every time I select an address from the address book for a new
message. 
I select the address - then press the To : CC : or BCC button and the
entire Netscape Communicator application closes.

I could understand the close when the application is requested to close.

If the internet address is manually entered in to the To or CC - works just
fine.

Does not seem to matter if under the K desktop or the GNOME x-windows
interface.