thumbnails

[norman]

When I open a folder containing photographs I sometimes get a thumbnail
of the photograph and other times a small, blue icon. Both thumbnails
and icons may appear in the same open folder. I have tried to make sure
that it wasn't the file size by setting, in preferences, show thumbnails
only for files smaller than 100MB. I may get files larger than 10MB but
not much larger.

Could someone please explain why this should be, please? Google has not
been of help.

Norman