Would you like to change your permalink structure from /%year%/%monthnum%/%day%/%postname%/ to /%postname%/? Are you worried that you will lose traffic when those pages are no longer indexed by the search engines?
Dean Lee has created a “301 redirect” plugin that tells the search engines that a page has moved permanently. When you use his plugin the SE's update their indexes quickly, you retain PageRank and you still get your traffic through the engines.
Safely change your permalink structure using Dean's plugin which is available at http://www.deanlee.cn/wordpress/permalinks-migration-plugin/.