If you want to know what the hell just happened on your system, run this command and it will show you the 10 most recently touched files in the current directory. If you do this in '/' it will take obviously a long long time.
find . -type f -print0 | xargs -0 stat -f "%m %N" | sort -rn | head -10 | cut -f2- -d" "
find . -type f -printf '%T@ %p\n' | sort -n | tail -10 | cut -f2- -d" "