I have an issue with a MacBook running Mac OS X where the network link comes on for a few minutes and then goes off and keeps coming on and off. Sometimes, the link stays active for a few hours and then it goes off again. Any tips on troubleshooting? Could this be a hardware problem? I ran the hardware test off the Mac OS X Tiger CD and everything came back fine, but I think that hardware test only tests the main logic board and memory and not the NIC. Appreciate any help or suggestions! Thanks!