Those other PCs/laptops you tried it on were all Vista? Or also XP and Windows 7? Finding another XP computer shouldn't be too difficult.
You might need to install Vista software/drivers for this camcorder if you installed the XP equivalent on your XP system. Did it come with installation instructions and a CD? Did you look at the Samsung site for possible software?
And there's always the option the camcorder is defective.
I've been using a Samsung mini DV camcorder for a few years now. Since I don't use it often I never converted the tapes to discs regularly. However I had converted a couple of them with the standard USB cable when I was using Windows XP. Since I upgraded to Vista the device is no longer recognized by the computer. Tried it on other PCs / laptop with same results.
I turned to Samsung website, C-net forums, youtube and other online sources for a solution but all of them suggest using a firewire port, which is not available on my PC or laptop. I'd like to know if there is any other solution, and more importantly why it worked on XP but not on Vista. Would upgrading to Windows 7 solve the problem?