SUID directories

[Keith D Gregory]

As an interesting note under HP-UX 7.0 . . .
 
If you make a directory, then do "chmod +s mydir", you make the directory
disappear.  Its inode is still in use, but there is no way to access the
directory.  I assume that its entry in the parent directory is somehow
corrupted, as I can make as many directories with the same name as I wish.
 
Any ideas why this might happen (addressed more-or-less specifically to
HP-UX support types at HP)?
 
-kdg