Photo Preview not available

Question

After downloading photos from my Digital Canon Ixus Wireless 5 megaixels, into my Vista Photo Gallery in order to review and enhance the photos, I can not do the enhancing because I receive sometimes an advertisement saying NO PREVIEW AVAILABLE. No preview nothing to
do about enhancing.!!! What can I do to avoid this situation of to correct
it. Many thanks.
Jose Oltio Espinoza, Bodrum, Turkey.
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