system: Debian-60-squeeze-64-LAMP 2.6.32-5-amd64

As root I create a user in an ssh-console:

useradd -m -G users myuser
passwd myuser
xxxxxx
xxxxxx

su myuser or after login via ssh I get:

\[\033[01;31m\]\u\[\033[01;33m\]@\[\033[01;36m\]\h \[\033[01;33m\]\w \[\033[01;35m\]$ \[\033[00m\] plus the cursor

Using the tab key the cursor just jumps forward, so no completion here.

Also the arrow keys do NOT work, if I use right arrow key I get:^[[C

What could cause this behavior?