Help! What's wrong with the third text widget??

I have several “Text” widget on the sidebar. Recently, the third Text widget items always behave wrongly.
The site is http://www.posAbilities.ca

If you look at the site right now, the sidebar item “event calendar” is not displaying like the others (the green title and the sidebar items in the white space below). I have tried experimenting and found that it is not the html within the widget but it is the *third* Text widget that behave this way.

If I move them around whichever is the third one will disply wrongly like this. If I put the subscription sidebar item as the third item, it doesn’t happen because it is not a text widget, but the text widget below it (which is now the third text widget will be wrong).

Can someone give me an idea as to what is wrong and how to fix it??

Thanks!