CSS alignment

I am trying to make the left side of a web page go the full height of
the browser when text in the body area exceeds the browser widow height.
I am getting some weird things happening right now with that. When the
text exceeds the height of the browser window, the left menu stops and
does not follow the text down when scrolling the window. 

Any ideas on this. Should I be posting this here? 

Thanks,
Nik