Linux v.2.4.0 and Netscape 4.76?

After making extensive enquiries elsewhere I have been advised to post
this question to the kernel mailing list. Joseph Anthony wrote recently
to the list about a similar matter (I think).

The problem: symptoms

It concerns the behaviour of Netscape after upgrading from kernel
2.2.16 to 2.4.0. With the new kernel Netscape locates and connects to
a URL, and sometimes begins to download, but then it just sits there
indefinitely (without downloading any data). This happens quite
consistently since I upgraded to 2.4.0 (about 2 weeks ago).  ppp,
telnet, ftp all function satisfactorily as far as I can determine
(however that's not to say that the problem doesn't originate with
ppp in the kernel). There are a few packet errors (about 1 per 1000).
Netscape continues to function well with Linux kernel 2.2.16 -- but
not with 2.4.0.

People have suggested various things (eg upgrading programs to later
versions). I have tried most of them, without success. Somebody
recommended I turn to the kernel mailing list. If this is not the
right place for my enquiry I apologize (where else?). But if somebody
recognizes these symptoms I would be very grateful for a diagnosis...

Thanks,
Roger Young
([e-mail])

Motherboard: GA-6VX7-4X with Via Apollo Pro AGP chipset
CPU: P3/733 MHz
Memory: 256 Mb SDRAM
Graphics: GA 660+ with NVIDIA RIVA TNT2A chipset (32 Mb DRAM)
Modem: Dynalink 56K external modem. Serial port IRQ4, I/O 03F8-03FF. 

Distribution: Slackware 7.1
Linux kernel: 2.4.0 (2.2.16)
PPP: 2.4.0
modutils: 2.4.0
XFree86: 4.0.1
Netscape: 4.76