Netscape shouldn't crash, if it and the network are properly configured. Some things to check:
Make sure that the MOZILLA_HOME environment variable is correctly set. If you installed Netscape under /usr/local/netscape/, for example, that should be the value of MOZILLA_HOME. Set it from the command line (e.g, "export MOZILLA_HOME="/usr/local/netscape"" under bash or add it to one your personal or system initialization files. Refer to the manual page for your
shell for details.
If you have a brand-new version of Netscape, try a previous version, in case the run-time libraries are slightly incompatible. For example, if Netscape version 4.75 is installed (type "netscape --version" at the shell prompt), try installing version 4.7. All versions are archived at ftp://ftp.netscape.com/.
Netscape uses its own Motif and Java Runtime Environment libraries. If a separate version of either is installed on your system, ensure that they aren't interfering with Netscape's libraries; e.g., by un-installing them.
Make sure that Netscape can connect to its default name servers. The program will appear to freeze and time out after several minutes if it can't. This indicates a problem with the system's Internet connection; likely, the system can't connect to other sites, either.