The source of the problem could be Windows because sometimes Windows just happens to crash at the right time and at the right moment. It could be when you are trying to save data or it just happens sporadically.
One solution to the problem is thatyou might want to check the integrity of the database to make sure that you can store new data in the tables and not get an error message when you save the data. You might also check to make sure that all of your fields, field types, field sizes, etc., are what you want.
If the integrity of the database is fine, try re-naming the database to a different name and running the database with the new file name.
If it works fine in both cases and the integrity is fine then the next solution is to try different operating systems. This will allow you to get different feedback from the particular OS that you are running the database.
Are you using it in a stand-alone environment or are you using it in a client / server environment?