I discovered bug in the new MacOS X 10.1.5 release, I passed it along to MacFixIt and they published it at the top of the Friday page. My comments were edited and not so clear, but the problem is simple. Some machines connected via cable modems will lose their DHCP settings when they wake from sleep. The new updated OS incorrectly drops the DHCP lease when it sleeps.
Now that I’ve been tracking the problem, I’ve noticed it is not consistent. I lose connectivity on my Powerbook about 80% of the times it wakes from sleep. This is the worst type of problem to diagnose, an intermittent problem. I’m not sure what the problem is, or why it didn’t get caught in beta testing. The problem is widely reported but not particularly common. I hope we get a fix from Apple soon.
Update: Apple released a fix within 48 hours of the problem’s discovery.