error, "SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM"

In Database Admin, restoring a Client's backup, I am getting an error, "SqlDateTime overflow. Must be between 1/1/1753  12:00:00 AM and 12/31/9999 11:59:59 PM"

What is this?

I write reports, and get client databases to work in. This is the first time I've seen this error, and not been able to restore their database.