Cannot download large files

Hello,

My home network is behind a netgear wifi modem/router.

Two win98 PC (connected wirelassly) have problems downloading large files. A
100-200 Ko file will download OK, but not a 10 Mo file.

It's as if the server connection was reset again and again. E.g., when
trying to download an antivirus update, the progress bar advances, then goes
back...

I tried TCP optimizer to find the correct settings, but it didn't help
(though it did boost the connection speed).

All the other networking functions work well (including browsing). Two other
XP / 2k PC do not have any problem.

I'm out of ideas... Any help greatly appreciated. TIA,

--
Daniel CLEMENT