One way IP traffic??

I have a small wireless home network comprising router (which is as a DHCP server), one laptop and one desktop. On initial setup, I had to set the IP address on the laptop manually as it did not seem to be able to run DHCP. Nonetheless it all worked fine until last week. Now the laptop cannot see the router or the desktop client when I ping them. However, the desktop client sees both the router and the laptop when I ping them from it!?

I have even set the router to have a fixed IP address, and the other two machines to addresses in the same range, thereby leaving DHCP out of it, but the result is exactly the same, i.e no replies when I ping from the laptop, but replies from router and laptop when pinged from the desktop.

I have run "netsh winsock reset" and "netsh int ip reset" but no change.

Your help really neede here.

Many thanks
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Fatal_ExceptionSystems EngineerCommented:
You might want to try some of the suggestions in this article, one of the best for troubleshooting TCP connections:

BTW:  I don't like software firewalls (Panda, Norton, McAfee, etc...) as even when turned off, they sometimes interfere with connectivitiy...  but then again, I run strong perimeter firewalls on my networks...  :)
What about netsh firewall reset?
have you got firewalls enabled?
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Fatal_ExceptionSystems EngineerCommented:
I would start by executing a series of PING commands:

Step-1: Ping Loopback IP address ( Success shows that TCP/IP is properly installed.

Step-2: Ping local NIC's IP address. Success shows that NIC is working properly.

Step-3: Ping Default Gateway. Success shows that local physical layer connections are ok.

Step-4: Ping Remote IP address. Success shows that remote physical layer connections are ok.

It appears that your PING will fail on 3 and 4, but see what happens with the first 2...   For instance, if #2 fails, then you might have a Device Driver issue...
mikegalsworthyAuthor Commented:
Many thanks for the suggestions

Johnb6767 - Have run netsh firewall reset - no joy

Jay_Jay70 - XP firewall is disabled but have Panda Internet Security installed. This firewall is still running - will disable and see what happens, although this problem has only just occurred after about 6 months of satisfactory operation.

Fatal_Exception - have done all the pings. Loopback and local NIC are both OK. No reply from router or other client, but as said in question, other client sees both router and machine in question.

Thanks and hope to here more
mikegalsworthyAuthor Commented:
Disabled the Panda Internet Security firewall and now is all OK.

Many thanks for your help, although I cannot understand why it became a problem after six months.
Fatal_ExceptionSystems EngineerCommented:
Ha!  Glad you got this sucker fixed!  Was really wondering if we could ever get to the bottom of the problem!

and thank you..

Fatal_ExceptionSystems EngineerCommented:
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