Have you finalised the discs in the camcorder before putting them into the DVD drive on your computer? You need to do this before the computer can 'see' the files and allow you to work with them. None of that software you list will allow you to open or edit mini DVD files (not so sure about Roxio, try it again after you've finalised the discs) but more than likely you will need some conversion software such as Super C or try STOIK Video Convertor 2, do a search on Yahoo or Google to find them.
Mini DVD files are awkward to work with to say the least. If none of that works then download a 30 day trial of Sony Vegas Studio Platinum 8 and see if that works or post again on the Sony Vegas section of the forum, where you will find more info and help.