I upgraded my MacBook Air to Mac OSX 10.7 (Lion) yesterday. Boy, there are a lot of changes, both under the hood and for the end-user.
One bug that I have hit is that after the upgrade both TextEdit and Preview crash on launch. I found one reference to this on a MacRumors Forum. I have determined that this bug is in no way related to Dropbox, rather with Mac OSX’s handling of symlinks.
I often create a /Downloads directory and then symlink this to ~/Downloads. This seems to be what causes TextEdit and Preview to crash.
To fix it, I deleted the ~/Downloads symlink, launched TextEdit and Preview, closed them, deleted the ~/Downloads directory that these programs created, and then re-created my symlink by running ln -s /Downloads ~/Downloads.
Apple has clearly made significant changes with respect to the filesystem. No one would accuse them of resting on their laurels. On that note, I’m certain this will be addressed in 10.7.1 if not sooner.