AUCTeX and undo-tree

[Greg Bognar]

I use the undo-tree package from GNU Elpa.  Recently, the undo command
(undo-tree-undo) stopped working when I edit .tex files with AUCTeX (in
LaTeX-mode).  As far as I can tell, it works as expected in all other modes.
Emacs seems to hang and I have to hit C-g repeatedly to be able to edit again.
The default M-x undo command still works.

Since I have a lot of customizations, it's possible the cause is somewhere in my
init file.  But before I try to track it down, I wonder if anyone else
experienced this problem and have some ideas.

Thanks!