The count on the number of characters in a filename is stopped at the first
period. e.g. trying to upload an image called "D. A. Pennebaker CU.jpg" returns
the error "File names must be at least three letters." After some slight
experimentation I found out that removing the periods allowed the file to be
uploaded, hence this bug report.
I doubt this is very common (or, for that matter, very critical); I can think of
only a few people who go by initials, and I imagine most people would try
renaming the file. Maybe just add a short note to the upload page?