Hello,

I am using Excel XP. I have a sheet containing approximately 800 active
rows with perhaps 25 rows actively calculating something. The sheet is
unprotected. Sheets are not grouped.

The problem is this: on occassion, the autofilter dropdown arrow does
not respond; that is, I click it, and it doesn't give me the list as it
normally would. Even after turning autofilter on and then off again
does not work. By some stroke of magic it suddenly works again later,
after I've given up on it and worked on something else.

What might be causing this and how can I avoid it?

Thank you.