Unable to ping default gateway

I have a Windows XP Dell D600 laptop. I connect to different networks at different places. At one location, I am unable to ping to default gateway.

The laptop has a wireless device in addition to the standard network interface.

I have DHCP enabled. Windows Firewall is disabled. TCP/IP filtering is dsiabled for all adapters.

I can access internet, mail etc but I cannot ping my default gateway nor can I access shared network resources (shared folders on other PCs). I cannot ping other PCs.

At other locations, I can access the network without any problems.