10.6 update disables full duplex ethernet
Restarted in 10.5.8 -- 100Mb connection worked fine.
Restarted again and back in 10.6, I fiddled with settings and found that by manually switching to "half-duplex" ethernet (under the "advanced" tab) internet connectivity returned. (Connectivity also resumes if I choose the "automatic" configuration, because that too switches over to half-duplex). Either way, the working connection seems a noticeably slower than 10.5.8, which I assume is the difference between half and full duplex.
Any ideas on how to restore the connection to full duplex?
2.66GHZ Dual-Core Intel Mac Pro, Mac OS X (10.6)