maui,
There are plenty of articles about the issue, and some fixes from Boeing. This issue was on the 777, especially the 300, but others have noted the same issue.
The auto gust modal suppression system on the tail causes a flutter that was so bad it was making crew and passengers sick in the back...
I believe it was new ANZ aircraft that were in the news...
Older thread on the issue...
B777-200 lateral oscillation in turbulence [Archive] - PPRuNe Forums