Sporadic failure of access point

I have a computer with an Intersil Prism 802.11b card in a mini PCI
slot. The OS is Debian "lenny" and the driver is hostap. The
computer serves as an access point.

Sporadically my wireless client loses its connection. On the client,
"iwlist eth1 scanning" shows access points but not mine.

On the access point computer I can run "iwpriv wlan0 reset 1" and then
my access point reappears in the results of my client running "iwlist
eth1 scanning", and my client can regain its connection.

Am I right in thinking that the access point for some reason stops
transmitting? The card is 4 years old, could it be a hardware fault?

Thanks
--
KM