When trying to reinstall 2011 getting this error : The key, Unknown\Components\BD8E ... could not be opened.

It looks as if originally, ATIH2011 was installed under a different (admin-)user-acount that has been deleted in the meantime. So you should try to find the key (should be located under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData and then take ownership of the whole key. After this, you have to add at least one local administrator (also SYSTEM would be recommended) or the whole group of administrators and give them full access to this key.
If you are not familiar with folder permissions, maybe this short tutorial will help a little (of course, in your case, you won't remove users and/or permissions): How to Change Folder Permissions

Also, although I am not a friend of so-called "registry cleaners", I use the software from Macecraft from time to time. It helps me to find orphaned registry keys nobody has permissions for - because the software will later complain that certain keys could not be removed due to lack of rights (maybe only happens after a more risky "aggressive" scan). Of course, this is not a general solution, but has already helped me a few times.