IP Networking

Hi all, one of my Sun Box facing the problem.
The network port i had set to Auto-Negotiated and i had edited the /etc/system/ file in the Sun box as below:
set hme:hme_adv_autoneg_cap=1
set hme:hme_adv_100fdx_cap=0
set hme:hme_adv_100hdx_cap=0
But when i checked the /var/adm/messages/, it shows
unix: SUNW,hme0: 10 Mbps full-duplex Link Up
The Sun Box can operate with the normal speed
Before this, this Sun Box is running at 100M/full, but one day, it not manage to boot into OS, when i change to the setting as mentioned above, i can run as normal. Then i plan to changed back to 100M/full duplex, but still cannot boot into OS. Therefore, now i run the Sun Box with the setting above
Do you guys have any idea on this?
Thanks