FWIW - mine now seems to be working again. See my last post here:
As you can see, it's still not perfect because access to the web config is still intermittent, but everything else does seem to be working again. I haven't changed anything.
It's especially frustrating becasue it seems impossible to track down a cause - I have a suspicion that next door were having similar issues with my network interfering with theirs, and they moved their router to the other side of the house. I'm not prepared to go round and ask. But like I said, my PDA still picks it up.
At the end of the day - I reckon it is not a Roku issue, but an issue with your network environment.