Dropped connections with Windows 98

I have a couple of Avaya World card gold cards and a Netgear MA 101 that I
use on an IBM 600 laptop running Win98. All of them will connect to the AP
and get a good signal. I can see them logging into the Radius server and
getting authorization but after a while, minutes or hours the connection is
lost and the only way to get it back is to reboot the computer and sometimes
even that won't work.
When I renew the connection I can always see the connection come through the
Radius server and show a good signal on the signal meter for any of the
cards but I can't ping the AP or browse the internet.
If I run a stream from a radio station or play a game it will usually keep
the connection up for a couple of hours but not always. The connection will
always eventually drop off, even yesterday I stayed on for about 4 hours
first but after that I couldn't get on at all with any of the cards.
This morning I got on with no trouble logged in to the internet for about 20
minutes, running a stream and then lost connection to the internet.
Rebooted and all was cool. I've been connected for over two hours.
Any clue as to what is happening would be welcome.

AG