I have disconnected the webcam, but nothing was changed.
I have tried connecting the VHS player to the TV with the same cables, and it works excellent. I have also connected a DVD player to the Roxio capture device using the same cables, but then there is no video signal and no sound.
I have connected the Roxio capture device to all 6 USB ports in the computer, one by one, and they all showed the same result: No video signal, no sound.
Switching between recording quality levels does not help. The Record button is always grayed.
However, I have noticed, that the Roxio program interferes with other programs. I installed it on another PC (Windows XP Home), and uninstalled it afterwards as it did not work. Now the Roxio program wants to install something in a genealogy program called Brother's Keeper every time I start that program. I suppose that the Roxio program is interfering with other programs, and that this is the reason for the problems.
I thank you all for your help, I appreciate it very much.