$folder = dir(.);
$folder->rewind() ;
clearstacache();
while ($file=$folder->read()) {
     if (is_dir ($file)) {
            do_some thing.......
     }
     elif (is_file($file)) {
             do_somethingelse.....
     }
......
.....
}

is_file() call in the above code does not return ture if the file size is > 2GB.

I was able to print $file, just inside the loop (meaning the folder object has the file in the filelist
and hence it is the is_file() which is filtering it out.
I tried other functions like file_exists(), is_readable() etc in place of is_file() without any success.