All Drupal versions up to 5.3 show the following error. When a user uploads an attachment, but then fails to click the [Submit] button, the attachment is not attached to the posting, but a tmp_xxxxx file is left behind in the initial upload folder, such as phptmp.

I would propose to change the upload module such that it deletes such tmp files immediately. If that is too difficult or impossible, they should be deleted through Drupal's cron task.

Hans-Georg