Cannot browse My Network Places with WPA-PSK

Please excuse this extra post but I felt the other post may have been a bit
confusing.

I have the following scenario.

D-Link DI-624 Router. with 4 port switch.

Laptop 1:. D-Link DWL-G650 Wireless Card.
Laptop 2: Intel ProSet/Wireless 2915ABG built inl Wireless Card

I also have another system (Laptop 3) wired to the Network

All systems running WinXP Pro SP 2 with all latest updates.

When I disable all security on the router and all wireless Laptops the whole
network works fine. Full Internet access and LAN access all round.

However when I set up security on the router and Laptops as

WPA-PSK problems start to arise with Laptop 2.

When the settings are as above then Laptop 1 can see Laptop 1 and Laptop 2
and Laptop 3 in My Network Places. However when Laptop 1 tries to access
Laptop 2 it gets the message that Laptop 2 is not available etc....

Laptop 2 only sees itself in My Network Places and therefore cannot access
shared resources on Laptop 2 or Laptop 3. It can however access Laptop 1 and
Laptop 3 by UNC names such as \\Laptop 1\data etc.It can also access shares
on Laptop 1 and 3 via IP address e.g. \\192.168.0.x\data

Both wireless Laptops still have full Internet access with WPA-PSK TKIP

Laptop 3, wired to the Network has no issues between it and Laptop 1 when
WPA-PSK is enabled on both wireless Laptops.. However Laptop 2 has the same
issues with Laptop 3 as it does with Laptop 1.

I have tried everything under the sun to sort this out but no avail. I need
to get it sorted since Laptop 3 is my backup machine and does scheduled
backups of the data on Laptop 1 and 2 and so must be able to access network
shares on Laptop 2.

I am at loss to find the cause of the problem. I don't know it it's a OS
issue, a hardware issue between Intel Proset/wireless card and D-Link DI-624
router or what???????

And I really do not want to run an unsecured wireless network.

Suggestions greatly appreciated.

Marek Gold