Newly pasted layer is invisible when not over the image

[Blighty]

When you paste a new layer you get a "Floating Selection (Pasted Layer)" in the layers dialogue. You now have 2 opltions:
1) Right click the Floating Selection layer and do To New Layer
2) Anchor the Floating Selection with the Anchor button in the layers dialogue. The Floating Selection will be merged with the active layer.
Most often 1) is the right choice.

To see the new layer there are 2 options:
1) use the Move tool to move the new layer into the required position
2) Image > Fit Canvas to Layers