So, you can do one of 2 things...

1) Find where you're accessing the database during the get {} of that property and wrap it in an if(!this.DesignMode) {} block like this:

if (!this.DesignMode)
{
    // put your code here....
}

2) If you don't want to be able to set the value in the designer (meaning you don't care about telling your LocationsBO which CompaniesBO to use in the form designer), then add the following attributes to your property:

using System.ComponentModel;

...

[Browsable(false)]
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]

Thse will prevent the form designer from evaluating the property and setting it in the .designer.cs file for your form.