@cloud9, according to the W3C XHTML validator you have 528 errors on your blog main page. Those really need to be corrected before we can figure out if there really is an issue with your sidebar or not.
Go to settings > writing and select "WordPress should correct invalidly nested XHTML automatically" and then click "save changes."
Now, starting with your latest post, open it in the editor, make one minor change such as adding a space and then deleting it, and then click "update post." Check your blog and if it is back to normal, you are golden. If not, open the next post and do the same thing till it goes back to normal.
Also since your blog is very image intensive, I strongly suggest that you go to settings > reading and decrease the number of posts to show on the main page to around 5, but do not do that until after you go through the above procedure.