ricardorsj@uol.com.br  wrote:
 > Our machine is now intermitent. When I ping some machine, I must wait at least one minute for it to respond. (other machines can talk normally). The only machine I can ping ok is our main firewall, any other it's very slowly to respond. The problem is 
  that although I can ping our firewall, I can ping no machine except that one. (yes, the configuration is ok because its working and the firewalls is forwarding packets for other machines).
 > 
 > I took the fxp0 off and put a ex0 in it's place but the problem persists. I even tried to connect it to another switch but it didn't help too.
 > 
 > Other machines can ping mine ok, but mine cannot ping others without a delay.

Your DNS server is having trouble.

prove this by using "ping -n <ip addr>"