Does anyone know if this pop up on a sales order is a feature that needs to be disabled or a script? "Items on this line have been drop shipped or special ordered.  Are you sure you want to modify it?"

That's standard functionality

1. Even if I was modifying these lines it's not an issue. The client creates orders that have a lead time of about 90 days in production so it's quite often that drop shipped item orders get modified prior to shipment. We use the functionality for the accounting end, it's not a true drop ship. 2. I need this disabled because suddenly when changing the sales order date, this pop up window appears and runs through each and every single line item before the record is able to be saved.

I'd be inclined to wait on creating the drop ship PO then. Or use some other method for creating the PO

LOL dude

if it's not true drop ship and only exists for accounting purposes.

this project is well past go live the process is fine

Well, there's probably no way to disable that.