The only time I've see this kind of problem is when I've used a macro to clean
up some shapes on the worksheet--and by mistake, I screwed up the autofilter
dropdown arrows.

Another thought...

Do you use merged cells in your header. Weird things have happened with them,
too.

HB wrote:

I create autofilter in my excel sheet. After using 2 or 3 times the filter
(filtering by the arrow), the arrows become in-operational. It is impossible
to change the fiiltering data.
I have to remove the Autofilter, un-hide all the rows and then create again
the filter.
Did someone faced this problem ? How to solve it

--

Dave Peterson