wireless frequently disconnections and eth0 question

[massimo]

Hi all,

i have two problem:

1)
my airport card connect an disconnect every 3-5 min. (under OSX all work
just fine)
in dmesg i found a lot of:

	eth1: New link status: Connected (0001)
	eth1: New link status: Disconnected (0002)
	eth1: New link status: Connected (0001)
	eth1: New link status: Disconnected (0002)

some one can help me to have a connection more stable?

2) 
i need to have eth0 working too, but if i assign it an address, all
connection go down.

here my /etc/network/interfaces
------------------------------------------------------
auto lo
iface lo inet loopback

#auto eth0
#iface eth0 inet static
#name Scheda di rete Ethernet
#address 192.168.3.119
#netmask 255.255.255.0
#broadcast 192.168.3.255
#network 192.168.3.0
#gateway 192.168.3.254

auto eth1
iface eth1 inet static
        address 192.168.3.19
        netmask 255.255.255.0
        network 192.168.3.0
        broadcast 192.168.3.255
        gateway 192.168.3.254
        wireless-mode managed
        wireless-essid WLAN
        wireless-key 2113555566XXXXXXXXXXXXXXX
        dns-nameservers 192.168.3.2
        name Scheda di rete Ethernet
------------------------------------------------------

if i decomment the eth0 part, every connection go down? why?
Note that under OSX i can have en0 and en1 (ehternet and airport) with
the same address IP without problem.

any help will be appreciate

ciao
MaX