I tried to reproduce this issue in Photoshop CS5. Even dragging the layer to the layer apron (the grey area outside the canvas) placed the image on a visible area of the canvas. What might be happening is the layer that is added is inserted above the currently selected layer. If the layer above it is larger than the layer being added to the document, the new layer could end up under the larger layer above it.
If anyone has steps to reproduce this problem, let us know and we'll look into it.