It's sad to read how a player can lose hours or even days of playtime because his/her game messes up somehow.
After having it happen to me more than a few times I save constantly now. In the old days of game playing it was considered wimpy somehow to save, and if you like to live on the edge I guess it is wimpy, but it's a real temper saver to have lots of backups.
It will pay you to save before you 'enter' any entrance, before talking to someone new, or at least every 15 minutes.
Saves take about a megabyte each - a bit more as the game advances. Thats about a thousand saves per gigabyte of hard drive space.
That's one heck of a lot of saves you can keep - so save often and don't erase your old saves.
If you start a new game you can remove the old saves and put them in a storage folder - that way no matter what, you'll not lose much should you have a problem and you can start again from anywhere in the game in the future.
Jinix the Elder
Men, today we die a little.
Emil Zatopek