If your trying to access an order and you run into an error that looks like this:
First, check the product of that order by going to SITE > Catalog > Products > [Product Name] > Pricing tab > Options & Adjustments > Maximum Quantity
In that field, check to make sure the Maximum quantity isn't using a value that looks like "99999999999".
Be sure to adjust it something a bit smaller like "9999999", then Save.
Return to your order, and it should become accessible again for you to edit.