How can I list all files in a directory and its subdirectories that have been created or changed since the system was booted. I was trying to acomplish this with "ls" and "find" commands but could not get anything usefull. Maybe some one can provide me a hint.

Thank you for your time.

Look at your start up scripts and find some file that is modified only at boot-up time. If you can't find one, add a start up script to touch a file. Now use find with the "newer" option.