Basecamp Initialization Cannot load the following areas: List Data File

This error appears each time I start Basecamp. I have tried uninstalling and reinstalling, along with deleting all Garmin files on my computer but it keeps happening! PLease can someone tell me how I can fix this? I have already lost a lot of precious data.....

I am using Basecamp 4.7.4 (the latest version) on a Windows 10 machine.