on my last computer, the usb wouldnt work. Couldnt figure it out for the life of me. But since your camera is detected, your hardware is working fine. I use XP pro, its stronger and not geared so intensively around ease of user by user. I dont think that would help but I do think there is something not playing nice on your pc. For instance, you said you see the preview fine but it won't record, that is strictly software. Its possible your ram is the problem. Many of the problems I see that dont make sense, its the ram. Software doesnt run 100% with some setups. That in itself is not common, but a solution nonetheless. IS your setup custom built or from a company? That would help me. also, have you tried other software? If you try other software with the same result, its a hardware/OS problem. If other software works, it was the previous software. Does this make sense? I'm trying to give ideas, I hope I can nail it down for you.