Unfortunately I seem to remember reading that once you have installed the Grim Fandango patch that your save game files created before the patch was installed will have to be deleted.
There is some hope though in that Lucas Arts used to have some save game files you could download that would get you past the bad areas in your own save games. I don't see them listed now but maybe if you write an email to support at the www.lucasarts.com
web site they can help you.
Short of that delete your save files and start over. (Actually I wouldn't delete them. I would just back them up to a different folder).
The support site does list a rather extensive fact on getting the game to run properly and it might help to go through that stuff too.