Matt,
Had you bought your Curve from a Local Bike Shop, then you could have taken it back there, but it sounds as though you are on your own here.
If the chain really is taught and the rear wheel central in the frame, then the chain should not rub on the frame. However, it is difficult to get the chain to the correct tension on the Curve after it's initial stretch from new. You can buy chain adjusters which will hold the wheel firmly, and these were metioned in a previous post on this forum.
The trouble seems to be that on re-tightening the wheel nuts after adjusting the chain the rear wheel has a tendancy to creep forward again, thus slackening the chain.
Try this :-
Loosen both wheel nuts. Note that drive side nut is hidden under the black plastic cover. Undo gear cable and pull of cover to access wheel nut. Keep locknut on gear cable close to adjuster so that you can maintain gear adjustment afterwards.
Pull wheel back to get chain tight (not too tight), but keep side of tyre in contact with inside of frame on the non-drive side.
Tighten the wheel nut on that side.
Now pull the wheel central in the frame and tighten the drive side wheel nut. The wheel should not slide forward again, since it is held by the tight wheel nut on the non-drive side.
Make sure that the chain is not too tight. If necessary go back and repeat the procedure with slightly more slack in the chain. Chains do not always stretch evenly and you may find that it is tighter in one position than another. Work to the slackest part and not the tightest.
Hope this cures your problem.
Les