Netscape crashing problem

I am running RedHat 6.2 on an Ultra1 and, every so often, the system
dies. Completely! Even the keyboard is dead so there's no option but to
switch off.

It usually happens when running Netscape (the 4.51 version that came
with the distribution) via a ppp link under KDE. The kernel is
2.2.14-5.8

It's unlikely to be a hardware issue because it has happened on two
different machines and different HDs.

Has anybody else had this problem? Or does anybody have any suggestions?
Any help would be greatly appreciated!

Regards,

Ralphe Neill

(Melbourne, Australia)