Repeating in explicit detail, since many people didn't understand the
first time:

in -current, netscape for linux 4.5PR2 (i.e. beta 2)
MD5 (/usr/local/netscape/netscape.old) = 2cae468d54a67126e9fecce41935467e
works just fine.

in -current, netscape for linux 4.5 release (i.e. what got released Friday)
MD5 (/usr/local/netscape/netscape) = 97914ae01ec6803d4b8a2ca987afad8c
dies a horrible death that indicates the kernel hasn't agreed it is an 
ELF executable.

file says this:
$ file /usr/local/netscape/netscape{,.old}
/usr/local/netscape/netscape:     ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), stripped
/usr/local/netscape/netscape.old: ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), stripped

Perry