Applications occasionally start showing "The document could not be autosaved" dialogs
It seems that this is actually a bug in Apple's sandboxing implementation. This means that none of the steps above should help. We had the same console output in one of our applications (including the inability to save text) and spent quite some time on finding the cause of the bug (see this radar). From what we've found out, it seems that after retrieving the recently opened documents for a number of times, the application cannot save files anymore because it does not get the permission to do so. You could try clearing the recently used documents menu, maybe this helps.
There's, in Lion, a hidden way of repairing permissions, which seems to be even more effective:
- Restart Lion, and Before you hear the chime, hold down Cmd + R, to access Lion Recovery.
- Click the Utilities item in the Menu Bar, then click Terminal.
- In the Terminal window, type resetpassword and hit Return.
- The password reset utility window launches, but you’re not going to reset the password. Instead, click on icon for your Mac’s hard drive at the top. From the dropdown below it, select the user account where you’re having issues.
- At the bottom of the window, you’ll see an area labeled Reset Home Directory Permissions and ACLs. Click the Reset button there.
It seems that this feature fixed the same problem to Dwight Silverman. Guess it's worth giving a try.
Apparently, repairing permissions with Disk Utility, as usual, does not repair Users file permissions.