The problem is with xp. Even though you don't have anything using com 1 XP has got bugs that prevent the edit software from Pronto to connect successfully. Go the control panel and under device manager remove com 1 from your system. Re-boot and it will be added back in and then you should be able to upload/download to your RC. I have to do this regularly with my XP system and Pronto TSU6000.

Let me know how it works.