I've trouble shot this enough to know it's an issue with your PHP Widget. I've used it for awhile and haven't had this issue.
I have two instances of it on my homepage. One if the tabbed feature where it says Basketblog, Game Center, Colleges. That looks good, but the issue comes with the widget area next to it. It bumped it down and would basically ignore the float set up. Until I added to my own code an extra /div.
I thought it was a theme issue until I used another instance of your PHP Widget in the footer. I had more tabbed content in there (and it might be there again by the time you look), but right now I just have "Hello" in there. It ignores the float and the widgets in the other two widgeted areas in the footer run down the page instead of across.
I've tried placing an extra /div in a few places, to no avail, both in your files and my files.
EDIT: Ok...now that I use a Title for the widget, the layout works well. Can you update this so it will allow for an optional Title?