You used dir() against a directory and then tried to open a file name you saw in the directory without including the directory in the file name to open.
You should use a code structure similar to:
projectdir = 'E:\scorpioncensus\reports';
dinfo = dir( fullfile(projectdir, '*.txt') );
for K = 1 : length(dinfo)
thisfile = fullfile(projectdir, dinfo(K).name);
fid = fopen(thisfile, 'rt');
data = textscan(fid, '%f%f%f');
fclose(fid);
... do something with the data
end
