attached is a patch to acroread-5.0.5.ebuild which removes the obsolete reference to /opt/Acrobat4 (the directory for acroread-4.05). I've also altered the ebuild slightly so that /etc/env.d/10acroread5 is automatically generated, but feel free to remove that if you like.
Created attachment 1106 [details, diff] acroread patch
*** Bug 2976 has been marked as a duplicate of this bug. ***
updated in portage. Thank you both for the fixes.