If you have cleared the Always ask before opening this type of file check box, you are always prompted when you use a link to a Tagged Image File Format image?
Use Regedit to view HKEY_CLASSES_ROOT\.tif\(default) and HKEY_CLASSES_ROOT\.tiff\(default). If either value is TIFImage.Document, set them both to Imaging.Document.
You could Merge the following .reg file:
REGEDIT4 \[HKEY_CLASSES_ROOT\.tif\] @="Imaging.Document" \[HKEY_CLASSES_ROOT\.tiff\] @="Imaging.Document"