As with most technology, problems can occur at any time--including this website uploader. There are a few things you can do to ensure a successful transmission.
First, consider compressing (zipping) your files before you upload. For a Windows computer you can download WinZip and for a Mac, just select your file and CONTROL + click to compress.
Next, make sure every uploaded file has a proper file extension at the end. For example, a zipped file would have a .zip at the end of the filename. Or a jpeg graphic file might have .jpg or jpeg at the end of the filename.
Finally, remember to leave any special messages or instructions if we haven't talked specifics about your file. Following these steps, along with keeping your files under 100 megabytes, can increase your chances of a successful file transmission. Thanks!