Win7 has wrong IP addr on ping, can only access with ip, not name

Hi all
Have read and tried everything here to get my Win7 PC to access my XP laptop using its name. Have 3 machines. 1 PC ( ip 192.168.0.102) and 2 XP Laptops (say LXP1 and LXP2), one is ...104 the other, the troublesome one, is ...101. If I ping the machine name
ping LXP2
I get the ping returning with the ip address of the PC (...102)
If I try to access LXP2 from Win7 PC, in Network in explorer - I am asked for the Password for the share. If I use the ip address 192.168.0.101 in the address bar at the top of explorer ( //192.168.0.101), the shares open and I can access the machine correctly.
Why does ping on the Win7 PC return the addr of the LXP2 laptop as 102 (the PC's address) but the LXP2 laptop IS correctly configured to have an address of 101 and it open on the PC with this address. This looks to me to be the reason that when trying to open the machine name (LXP2) on the PC in Network in explorer, it fails and askes for a password. The other laptop works perfectly every time. And the 2 laptops can 'see' the shares and access them on the PC. Both laptops can see each others shares and can be accessed. Its 'just' the Win7 PC to LXP2 access that appears faulty.
I tried disabling 'Network Discovery' at a suggestion on this forum and that did briefly work. But this morning - its back to its old self again, will only work when using the ip address... WEIRD?

Cheers
Paddy

Are you assigning the IPs, IE using static IP addresses? Because if you are the addresses you are assigning are inside most routers default DHCP IP address range. Usually most router use xxx.xxx.x.100 to xxx.xxx.x.150. This will definitely cause a conflict.

Also the Host names of the computer on any LAN are stored on the computer that becomes the Master Browser.

Hi Edwar
Some additional stuff. The router has DHCP enabled and all the ip addresses there are correct, PC is 102, LXP1 is 104 and LXP2 is 101 (its also 108 as sometimes I plug a network cable in, its on the wireless at the mo. as is the other laptop. Only the PC is connected directly. )

When I disabled and then re-enabled Network Discovery yesterday, as I said, the machine name access worked twice for 10-15mins, third time it was ok all day until I hibernated the PC and Laptop before bed last night. This morning, the LXP2 laptop responds on trying to open it on the PC with 'Enter Network Password' , which just results i nthe box re-appearing. This doesn't happen if I open the //192.168.0.101
The master browser is the PC (102) - I can not find any reference to the ip addresses for the 2 laptops or the PC in the registry.

I just pinged LXP2 (101) again and the ping got 4 replies from 102 (the PC)
If I
ping 192.168.0.101
the LXP2 laptop, I get a reply from ....102: Destination host unreachable.
Ping stats for ...101 sent: 4, Received:4, Lost:0

WEIRD! could this be something to do with the router.. though no changes have been made to this (well or anything else either!) It feels like something is wrong on the PC (win7, main machine)

Thanks for your help...

Cheers
P