I am getting an Internal Error when launching MYM.
After making a new backup of your broken data as it currently exists, the first thing to do is try is to replace the little.dbs in the broken dataset (corresponds to the folder name under the root MYM folder -- i.e. CURRENT), with a little.dbs from a recent backup. Usually, this fixes the problem. If not, try installing a new little.dbs file from the original install disks. If this doesn't fix the problem, try replacing the budget.dbs in the broken dataset with one from a recent backup. If that doesn't work, then we need to determine if another file is causing the problem, or your data is corrupted and needs to be fixed manually. Try these steps and let me know how it goes.