Quote Originally Posted by Jonathan183 View Post
I think your problem is caused by mount of hda1 ...
Jonathan, you're a genius! Of course it's so bloody obvious now you've pointed it out; the noexec option prevented bash (or anything else) from working.

The history of this is that hda1 used to contain my Ubuntu system, which I sometimes wanted to access from Debian. To make life easier for myself, I made it user-mountable. And of course "user" implies "noexec". When I created the Gentoo partition there instead, I just went on using the existing fstab; I never considered that it needed to be edited. I've edited it now and chroot works just fine.

Mike, it wasn't the way /proc was mounted. It's OK the other way too, provided that hda1 is mounted with normal defaults (as it would have been in Ubuntu Live, obviously).