Cannot upload as non-admin

I created a new content type using CCK 6.x-2.9 and added a file upload field using filefield 6.x-3.9. As an administrator, I can upload files fine. As a normal user (who has been given permission to upload and view uploaded files, as well as permissions to the various fields), I get a pretty ugly bit of code back:
{ "status": true, "data": "\x3cdiv id=\"edit-field-test-upload-0-ahah-wrapper\"\x3e\x3cdiv class=\"form-item\" id=\"edit-field-test-upload-0-upload-wrapper\"\x3e\n \x3clabel for=\"edit-field-test-upload-0-upload\"\x3etest upload: \x3c/label\x3e\n \x3cdiv class=\"filefield-element clear-block\"\x3e\x3cdiv class=\"widget-preview\"\x3e\x3cdiv class=\"filefield-file-info\"\x3e\x3cdiv class=\"filename\"\x3e\x3cdiv class=\"filefield-file\"\x3e\x3cimg class=\"filefield-icon field-icon-application-pdf\" alt=\"application/pdf icon\" src=\"http://nursing.kent.edu/apply/sites/all/modules/filefield/icons/application-pdf.png\" /\x3e\x3ca href=\"http://nursing.kent.edu/apply/sites/default/files/Projects Overview_2.pdf\" type=\"application/pdf; length=38077\"\x3eProjects Overview.pdf\x3c/a\x3e\x3c/div\x3e\x3c/div\x3e\x3cdiv class=\"filesize\"\x3e37.18 KB\x3c/div\x3e\x3cdiv class=\"filemime\"\x3eapplication/pdf\x3c/div\x3e\x3c/div\x3e\x3c/div\x3e\x3cdiv class=\"widget-edit\"\x3e\x3cinput type=\"hidden\" name=\"field_test_upload[0][UPLOAD_IDENTIFIER]\" id=\"edit-field-test-upload-0-UPLOAD-IDENTIFIER\" value=\"2f47d8fb45be4a42f6110cf74e81aeea\" class=\"filefield-progress\" /\x3e\n\x3cinput type=\"hidden\" name=\"field_test_upload[0][fid]\" id=\"edit-field-test-upload-0-fid\" value=\"451\" /\x3e\n\x3cinput type=\"hidden\" name=\"field_test_upload[0][list]\" id=\"edit-field-test-upload-0-list\" value=\"1\" /\x3e\n\x3cinput type=\"submit\" name=\"field_test_upload_0_filefield_remove\" id=\"edit-field-test-upload-0-filefield-remove\" value=\"Remove\" class=\"form-submit\" /\x3e\n\x3c/div\x3e\x3c/div\x3e\n\x3c/div\x3e\n\x3c/div\x3e\x3cscript type=\"text/javascript\"\x3ejQuery.extend(Drupal.settings.ahah, { \"edit-field-test-upload-0-filefield-upload\": { \"url\": \"/apply/filefield/ahah/test/field_test_upload/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-test-upload-0-ahah-wrapper\", \"selector\": \"#edit-field-test-upload-0-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/2f47d8fb45be4a42f6110cf74e81aeea\", \"url\": \"/apply/filefield/progress/2f47d8fb45be4a42f6110cf74e81aeea\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-test-upload-0-filefield-remove\": { \"url\": \"/apply/filefield/ahah/test/field_test_upload/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-test-upload-0-ahah-wrapper\", \"selector\": \"#edit-field-test-upload-0-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_test_upload_0_filefield_remove\": \"Remove\" } }, \"edit-field-test-upload2-0-filefield-upload\": { \"url\": \"/apply/filefield/ahah/test/field_test_upload2/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-test-upload2-0-ahah-wrapper\", \"selector\": \"#edit-field-test-upload2-0-filefield-upload\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"bar\", \"path\": \"filefield/progress/8990f833699d691ac121639e445ebb48\", \"url\": \"/apply/filefield/progress/8990f833699d691ac121639e445ebb48\" }, \"button\": { \"op\": \"Upload\" } }, \"edit-field-test-upload2-0-filefield-remove\": { \"url\": \"/apply/filefield/ahah/test/field_test_upload2/0\", \"event\": \"mousedown\", \"keypress\": true, \"wrapper\": \"edit-field-test-upload2-0-ahah-wrapper\", \"selector\": \"#edit-field-test-upload2-0-filefield-remove\", \"effect\": \"fade\", \"method\": \"replace\", \"progress\": { \"type\": \"throbber\" }, \"button\": { \"field_test_upload2_0_filefield_remove\": \"Remove\" } } });\x3c/script\x3e" }

Any help would be greatly appreciated. I've looked through the issues, but no-one seems to have opened an issue specifically for this issue. If you need any additional info, please let me know.