I knew first because sidebar at the bottom is always due to bad html somewhere (and clicking on each post title will tell you where), second because I viewed the sourcecode of that post afterwards to make sure.
To satisy your curiosity now, I visited a cached version of the post; your post was like that:
Notice the 6 stray div tags?
And you've got other trash HTML too (not related to the sidebar problem): the table cells with the images have two contradictory span tags and one p tag enclosing the image, all of them unnecessary. I don't know what you're using to create those tables (smells like... Word), but you'd better find another way!