Problem with ETH0:1

[Franco]

Hi, i have 2 subnet on my network 80.xxx.xxx.xxx and 82.xxx.xxx.xxx,
i have a FC2 with a ip NIC 80.xxx.xxx.xxx and i have added a virtual NIC 
eth0:1 with ip 82.xxx.xxx.xxx it work fine but in some case eth0:1 gone 
down without error in the error log or other.
When i restart a network /etc/init.d/network restart it don't come
back up. I need /sbin/ifup eth0:1.
Any idea to resolve?
Thanks.