Dropbox, Aperture and RAW.

Were the referenced originals in DropBox? Did oyu copy them out of DropBox before you discontinued it?

Please explain, what Dropbox has to do with your original referenced RAW files. Did you relocate your referenced files into your Dropbox folder?

Restore the originals from your most recent backup, that includes your Dropbox folder and use the command "File > Locate Referenced Files" to reconnect your image versions to the restored originals.

See this section of the Aperture User Manual, the paragraph "Reconnecting Missing or Offline Referenced Images":

http://documentation.apple.com/en/aperture/usermanual/index.html#chapter=5%26sec tion=16

All my pictures reside in a file structure.

Then point Aperture to these folders using the command "File > Locate Referenced Files" from the main menu bar.

"Reconnecting Missing or Offline Referenced Images":

http://documentation.apple.com/en/aperture/usermanual/index.html#chapter=5%26sec tion=16

To reconnect an offline referenced image

1. Reconnect the hard disk holding the referenced image’s master, or otherwise locate or make the file available to Aperture for reconnecting.
2. Select the project that contains the offline image you want to reconnect, or select the offline image in the Browser.
3. Choose File > Locate Referenced Files.
4. If necessary, click the Show Reconnect Options button.
5. At the top of the dialog, select the file path for the master that you want to reconnect.A thumbnail of the image and some identifying metadata appear
6. In the bottom half of the dialog, navigate to the location of the referenced image’s master on the hard disk and select the master.You can follow the file path listed for a selected image in the top of the dialog.When you select the file, a thumbnail of the image and metadata appear, allowing you to compare them to the thumbnail and metadata in the upper part of the dialog to make sure you’ve selected the correct file.
7. Click Reconnect to reconnect a specific image, or click Reconnect All to reconnect all selected images.

This is getting confusing, are the original files not found by Aperture (do the images have the warning icon saying the file is not available or off line) or does Aperture see them but is not able to decode the Raw files (Unsupported Image format)?

If is sees them but cannot decode them try to reprocess the raw files.