Your problem is definitely related to your template and css definitions (so doesn't have anything to do with a theme being at fault).
If you install Web developer and activate View Style information under button CSS you'll see that your columns are part of the same div (mouse over the page and see the red squares and css path defined for it and it your case overlaying each other).
If you want 3 columns you should define a main div (often called mainwrapper) en 3 separate div's inside that div.
If you let them all float:left they will be next to each other as long their width allows it (work with percentages for the separate div's).
Web designing can be a pain in the ass sometimes..................
Quality is in the detail of things............
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