Realtek 8180 PCI cards losing wireless connection

I have a D-Link DI-514 Wireless router with 4 computers all linking to it
via wireless cards and a couple of print servers attached via wired
connections.

All of the computers are running XP Pro.

Two of the computers are laptops with PCMCIA cards. The seem to connect
fine, although the connection seems to drop for a few seconds every now and
then.

I have two desktop computers with Realtek 8180 wireless PCI cards. Both of
these desktop can see the wireless connection and are assigned IP addresses
by DHCP. However, they keep dropping the connection. If I try pinging the
router I get a dropout rate of between 20% and 100%. The signal one both
computers is very good.

I have tried reducing the speed from 11Mbps to 2Mbps. I've also tried
reducing the RTS threshold and fragmentation and increasing DTIM. All have
no effect and only cause problems on the other two computers.

One of the desktops has been upgraded to XP SP2, the other has not.

I am running WEP although I don't think this is the problem. I have
experenced the same problem with it turned off.

I am beginning to wonder if the Realtek cards are both faulty or deaf.

I have had this problem using the newest drivers.
Try using older drivers.