This is the strangest problem I have ever seen. I have a laptop on my network, it receives dhcp settings, and can ping the server dealing out the dhcp. It cannot ping the gateway, it cannot ping my dns server. If I assign static ISP dns servers it still cannot ping anything. Obviously I have no internet access. I can ping some computers on my network, but not all. I have checked the cable, the jack, I've installed another NIC, I've removed any hubs or switches in the mix, I've flushed my dns, I've statically set the arp settings in a computer that could not ping it. If I set my wireless to a nearby different LAN, it goes right in. Here is the kicker: It only happens sometimes. Some days I plug in and it works perfectly, some days I get nothing.
I'm at my wits end. If it were my computer it would already be reformatted. My boss has told me in no uncertain terms cannot I reformat that machine :)

have you checked ICMP? Or firewall settings? If it happens randomly i would check to see if the actual hardware on the machine is working. Are there any diagnostics you can run for the hardware?

Firewall is off, we even removed any antivirus programs just to be sure. The hardware works great when I bring it home and plug it in, I'm looking into ICMP now. but EVERYTHING works great on another LAN. W E I R D!

make sure that you don't have any 2.4 ghz phones around. Because when some1 turns on that 2.4gzh phone it will interfere with your 2.4ghz wireless card/usb or any thing that works on the 2.4ghz signal.

My wireless works flawlessly, this problem is a wired issue. Maybe I was unclear.

If you open a dos box and try the following command, is there configured any standard gateway?

ipconfig /all

Yes, I get the same gateway and dns info of every other machine in my network. Even if I statically set my IP info, i can ping some machines but not others. And conversly, Those machines I can ping can ping me back, but those I cannot, cannot ping me.

"cannot ping me."

You have to have a firewall engaged. Its the only explaination for your events.

You logon one network and "works great on another LAN" but a different lan and its ip range you can't be pinged.

Engage the windows firewall. On the lan you can't be pinged, add that subnet to your trusted list.

Imagine the power of knowing how to internet search
http://www.lib.berkeley.edu/Teachin...

No firewall enguaged, at all.
Tried what you said, still no good. In the meantime also tried updating the nic driver.

What kind of device is your standard gateway?

Do a tracert to lets say google.com ends at your standard gateway?

Your router may be going bad on you, or at least the wired side of it. If you can get your hands on another, unplug the existing one and try the other one and see if it works OK. If it does, then you can be fairly certain there's something wrong with your router.

20 other somputers work great with the existing router. New ones have been installed since this one. I'm going to try a pcmcia nic tommorrow, and see if it helps, maybe arp poisoning, but I dunno.