Yes, Photoshop has a built in currency detector for US and Euro bills. If the bill's size fits within a certain size/resolution, you can't open the image files (as you've found out). I can't remember what version that kicked in (I think it was CS2 or CS3). You might try opening the image with some other app and see if it works. There's a sweet spot where the bill makes Photoshop punt, if you can use something else to get the sizes down, you might be able to get it into Photoshop for saving to the web.