First, make sure you are using 1.22a of Ghost Action. This should sync
to iCal on Leopard.
If you have the right version and it still doesn't work, try to backup
you iCal data from within iCal using File -> Backup iCal... Then do
File -> Restore iCal... This will reset the sync engine for iCal,
which seems to have become confused. Now try to sync with Ghost Action
again.
If this causes duplicate calendars, carefully remove the calendars
from iCal that doesn't have any data in them.
Best regards,
Jacob Wallström
http://ghostparksoftware.com