Ethernet detects but not working

[siva9900]

I had installed Mac OS X 10.5.2 on my GA-M51GM-S2G motherboard. From the installation disk the LAn drivers doesn't work so i downloaded other one and installed it after installation the system detects ethernet but as soon as it detects the LAN switches OFF and my ADSL router too LAN light switches off.WHen i restart when it is at bios it starts detecting LAN and even in windows it is ON. As soon as i switch to mac it switches off. could any please say what the problem is.I will be thank full to it

 

Thank you