EJab

(emacs) Keymaps says:

"As a user, you can redefine any key; but it is
usually best to stick to key sequences that consist of
`C-c' followed by a letter. These keys are "reserved
for users," so they won't conflict with any properly
designed Emacs extension. The function keys <F5>
through <F9> are also reserved for users. If you
redefine some other key, your definition may be
overridden by certain extensions or major modes which
redefine the same key."

_Please_ use something other than `C-c j' as your
prefix.