I noticed this after upgrading my site to WP 2.2. and using the search function.
I have a search box oon my sidebar. Using it returns the 404 page. That same search form code is ON the 404 page and when you use it from the 404 page it works. The code is copy/pasted from the 404 page into a text widget for the side bar. I am stumped as to why it doesn't work anymore from the sidebar. Any ideas?