Yahoo assure me that they are on the case but as you will have noticed, the site is down for a fourth day :(
Hopefully we'll be back in action soon.
Jo
Hello Jo,
Thank you for writing to Yahoo! Groups.
We sincerely apologize for this issue with receiving an "Invalid Group"
error when attempting to access the message archives in your Yahoo!
Group. At this time we would like to reassure you that we are doing
everything in our power to resolve the issue as quickly as possible.
Although we can not offer you an estimate as to when this problem will
be fixed, please be assured that we are aware that the problem exists
and our engineers are further investigating the issue.