Cannot turn off input method (C-\ undefined)

[Mirko]

Hello,

in my version of emacs 22.0.93.1 (AucTeX built for windows), I cannot 
turn off the input method using C-\.  The key is undefined.

According to the documentation, that key should be defined by 
default.  Am I correct?

I got out of the predicament by using inactivate-input-method.  But 
since it is not an (interactive), I had to do an M-x eval-expression 
(inactivate-input-method).

So, I am just confused about the status of the C-\ key.

Thanks,

Mirko