invalid mac address detected "booting problem"

hi everybody'
I am using using ubuntu 8.10 in my laptop along with win vista.my lap config is
AMD turion 64X2 2ghz processor;
2gb ram
nvidia graphics,ethernet.
The problem is my computer doesn't boot on it's on.Every time I boot I have to keep on pressing any key to start.It stops initially givnig "invalid mac address detected" and"switching to random mac".
Can any one help me please....

Harshavardhan