Type this again after typing "exit", before typing "./chrootarch":

cd /home/user/archlinux

When you use sudo gainroot, and then change the directory with the cd command, the directory change doesn't carry over to the non-root shell you started with. So if you start at /home/user (shows us as ~ in terminal when you're non-root), then sudo gainroot, then cd to, say /blah/whatever/blahblah, then exit, you'll "exit" back at /home/user.

That's what's happening here. When you cd to /home/user/archlinux as root, you end up exiting root at wherever you started (default being /home/user on the N900).

So you can either run the first "cd /home/user/archlinux" before "sudo gainroot", or run "cd /home/user/archlinux" again after "exit".

BTW, you don't have to keep running the chmod commands anymore - if they worked once, and you haven't deleted those files since then, or overwritten them, the permissions (that's what chmod does - changes permissions) should remain set.