Do you have the CONVERT NULL DATES TO DEFAULT option set?
Open the report
Click FILE --> REPORT OPTIONS
Is the option CONVERT DATABASE VALUES TO DEFAULT checked?
Is the database actually returning that date?
You could also suppress the value with a formula
Right click the field
Click FORMAT FIELD
Click the COMMON TAB
Click the FORMULA BUTTON to the right of suppress
{YourField} = Date(1900,1,1)
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