Grey Column menu suddenly stops and becomes white

On my website there is a white block visible were it is not supposed to (under the left menu). When you scroll down the page, the grey menu/ column on the left suddenly stops and the white block appears. Sometimes it is larger then other times. And now and then it even disappears. Can somebody explain to me how to repair this?
Here is the URL of my website: www.globecosmetics.nl/ . Surf through it to see what I mean.

I tried to replicate that but with no success, can you tel us what browser do you use and if would be good if you cant catch snapshoot of that.

www.globecosmetics.nl

This is the complete address. It should work. Let me know if it doesn't.

???

Your web browser is:_______________

??? That went wrong:( Hopefully now: www.globecosmetics.nl/

no, it doesn't seem to work. It is http:// if that is what yoy mean