Can you start regedit.exe and go to the following section?
HKEY_CURRENT_USER\Software\Allround Automations\PL/SQL Developer\Preferences
- If an AutoAlignSQLGrid value exists, set it to 0.
- If an AutoAlignSQLGrid value does not exist, create it as type DWORD and set it to 0.
This should fix the issue, which is fixed in the current 10.0 release.