[Plugin: NextGEN Public Uploader] Upload error

Does it say HTTP error on the upload? Probably has to do with memory limitations. Check the error log in wp-admin/. If there is mention of not enough memory, then contact your host and ask them to change the memory limitation. That is what I did and it worked. Do a search on Google and you will find many sites discussing the dreaded HTTP error upon media upload.

elimc is correct, this error is due (typically) to the PHP settings upload_max_filesize and post_max_size. You can either increase them via php.ini, or via .htaccess. Depends on your hosting situation.