I have photoshop cs6 and I suddenly can't save as jpeg anymore. When I click Save As I only have a couple of options left, weird files like raw and psb, together with psd. How do I save to jpeg??? It did work normally with Save As before.
Try flattening your image, maybe? Even if it's super big it should still be able to save as a jpg. Try using the 'save for web' option and see what happens there.
I think in CS2 you just get a warning that it will not keep layers, but it might be different in yours.