It happened, that when I upgraded to Lion, for some reason Preview stopped working. This was new to me - usually I don’t expect such behavior under Mac OS. Seems that lots of people had this, especially the ones that have upgraded MBP with SDD and having HDD at the place of Optical Drive. In this case you make SymLinks in your home directory pointing to HHD for Downloads (for Photos, Music, Movies or anything that you can afford to play from slow media and takes more space, which is expensive on SSD).
The FIX: Remove the symlink for Downloads, start Preview, create symlink, start preview again:
killall -9 Preview cd ~/ rm Downloads open -a Preview killall -9 Preview ln -s YOUR_LINK_DIRECTORY_FOR_DOWNLOAD Downloads open -a Preview
UPDATE: The same happened with TextEdit - I suppose it will be for all programs that use one and the same IO with Downloads. So in case it happens, just replace