Digital Ixus v3 not found

I have a Canon Digital Ixus v3, but cam2pc fails to recognize it at all. I did download and install the additional software for Canon cameras.
When I set file transfer to PTP mode Cam2pc tries to find a Canon camera for one second or so and then switches to Sierra, but nothing happens and after a while the detection window freezes. When I set file transfer to Normal mode, I get the message: Cam2pc was unable to detect your camera. :cry:
I use Windows XP Professional SP1, which has no problems recognizing the camera. I have not installed any Canon software that came with the camera. Can this be the problem?
Any suggestions?
Peter
When I set file transfer to PTP mode Cam2pc tries to find a Canon camera for one second or so and then switches to Sierra, but nothing happens and after a while the detection window freezes. When I set file transfer to Normal mode, I get the message: Cam2pc was unable to detect your camera. :cry:
I use Windows XP Professional SP1, which has no problems recognizing the camera. I have not installed any Canon software that came with the camera. Can this be the problem?
Any suggestions?
Peter