You have saved the error in your save game. You should follow the adventure gamers credo of "save early and save often". That way you never have to go back very far to recover errors or mistakes.
There will be no re-release as Sierra no longer exists. Even though I have the release candidate of Windows 7 installed, I have not done much experimentation on it yet. It is a little early to expect to be able to find a lot of information on making older things run on it since it isn't even on the shelves, yet. Backwards compatibility fixes for old games can take time for people devise when a new release of Windows comes out.
You can try experimenting yourself by playing around with settings for compatibility mode, hardware hardware acceleration, new drivers, etc. If you have the pro version of Windows 7, you might try "XP mode", but I have yet to try it myself. If all else fails you can try a virtualizer like Virtual PC or VMware.