Error, unknown mail format!

[imputerate]

1. ubuntu, beta-hardy crashed; i rebooted;

2. loaded emacs, then gnus:
got the expected:
Gnus auto-save file exists.  Do you want to read it? (y or
n)

3. hit 'y' and then got this:
Error, unknown mail format! (Possibly corrupted buffer ` *nnmail
incoming*'.)

nothing gnu-ish showed up on screen;

4. 'list-buffers) yielded:
CRM Buffer Size Mode
File .
*Group* 783
Fundamental
*scratch* 0 Lisp
Interaction
* *Messages* 1408
Fundamental
% *Quail Completions* 0
Fundamental
.newsrc-dribble 79673 Fundamental ~/.newsrc-
dribble

5. tried to load "Group", but got only a blank screen;

So, looks like i have no access to gnus; what can i do?