In this mode the mirror is not staying up when you wind on. It's not behaving like any camera with a true lockup where the mirror stays out of the mirror-box during operation (eg. single digit F-Nikons). It goes half way down and flips up again (as does the 500 EL-series in AS btw.). I know you have a 2000. Take it out, try it and you'll see!
Stefanm (aka Kwafump on hassi-foto.de)