I want to use my 350D with either Nebulosity or EOS utility but as soon as I plug it in and turn the software on, the camera says busy and stays that way.
Do you have any images on the card waiting to be transfered to the PC?
Maybe try a different CF card or take the card out or try connecting to the camera through camera window or zoom browser.
Are u on vista? If so, u need new drivers. Also, I have to ensure that the bulb lead plug into the camera sometimes has to be a mm or two not in. To do this I cut a small piece of thin rubber around the connector. Not sue if this is a problem for u but it has been mentioned before on IIS.