Corrupt File Upload

For our ecommerce store, we have a backend that allows employees to upload product shots. These images are then resized to fit the design of the website.

For a while now we've been having an issue with some very weird distortion in the images. Here is a sample of the distortion:

Reuploading the image usually fixes the problem, but it's been getting worse and worse.

Today, I took at look at the original uploaded files, and I see that the distortion is there in the original file. I know that they are not being uploaded like that, so the corruption is happening during the upload. Any idea what might cause this?

The originals are produced in Photoshop on Mac, and uploaded using Firefox on a Mac.

Here is the code that uploads the file

        <cffile action="UPLOAD"
            filefield="form.imageFile"
            destination="#UploadPath#"
            nameconflict="makeunique"
            accept="image/gif, image/pjpeg, image/jpeg, image/jpg, application/pdf">

So as it turns out, the issue is was specific to that computer and that browser. Seems that that specific Firefox was corrupting files randomly on upload.

Using a different browser, even on that same machine, has resolved all the issues.