There are many situations where 6.8 will allow you to enter input that is not valid, but it saves anyway. You have probably run into one of those.
Does this happen when you open the .backup file initially or when yopu save the results?
If it's when you open the file, then I can't tell exactly unless there's more to the error message.
If it's when you save, then try unchecking each of the items on the right and save again to see if it's one particular list that has bad data in it.
You can also send me the .backup file to my McAfee email and I can look through it to determine what's broken.
I receive the error when I click on open in the conversion tool on the configuration file. What address should I send the config file to?