I first posted about broken vhd – avhd chains in December 2009, And since then I have helped many people throughout the world in recovering their data and made some friends along the way.
I have recovered data for people in france, germany , uk, australia, usa, brazil
A guy called Dave Loughner from Innovative Solutions in New York pointed out a great utility for recovering data from avhd & vhds.
It is Disk Digger and only cost $14.99, Best money you will ever spend if your really stuck. Dave tried about 30 recovery products before coming across Disk Digger.
As of writing this http://www.diskdigger.org is down but you can download it here
Also a point to note. The disk digger solution is absolutely the last resort as nothing is as good as merging all avhds and having a healthy server at the end.Using disk digger will get you back up to 50% of your data but not all.