Yeah, that frustration is a mega killer. But then, look at the bright side. I was well on my way to making a pretty cool map when I accidentally saved the small flat jpg I used for uploading as the main psd file. I was about to choke myself but after a week I started a new map and it became The Butcher, The Baker, and That Other Guy...one of my best maps ever. So while you will choke yourself for a while, you've got a chance to do something even better...every map is a learning experience.