Anyone know why Photoshop Elements keeps changing my photos' resolution to 72 ppi? When I open an image for editing, the program automatically changes the image's resolution to 72 ppi. I look at the file information, and it tells me that the image has a resolution of 180 ppi. But if I save the file (even without doing anything to it) it gets downsampled (is that the right word?) to 72 ppi. Why???

Can someone help me? I'm sort of new to this. I've already reset all tools, and I can't seem to find anything useful in the help file or on the Web. TIA...