It would be helpful to know your scanner make and model, but just off the top of my head there a some generic settings to most desktop scanner models. First you want to check to see if you have any default unshrap masking settings active (usually there are) and turn them OFF. Secondly, try scanning at a much lower resolution or magnification - or both. Some scanner interfaces don't show these choice at the Basic Settings Menu but can be arbitrarily set at the Advanced Settings Menu. try a combination of settings that will give you approximately a 1024 x 768 pixel file. This will be different each time depending upon your original art size and desired resolution.

For instance, an 8 x 10" art piece scanned at 100 pixels per inch and 100% magnification will be a 800 x 1000 pixel file. A 4 x 5" drawing at 200 ppi at 100% is the same. Or you could keep the res at 100 ppi and scale at 200%!!!

Nice work by the way - both of you!!