I am having the same problem as the OP with my Insight.
I just purchased a Download cable and it will not download any Dives. I am connecting the plug Logo Up to the computer.
I installed the USB Driver: 775.2k_Vista_USBDriver.eve that was posted on 5/28/09 and the Software 673.Sherwood_Computer_Interface_2.0.4_Setup that was posted on 12/08/08. I am running Windows XP Service Pack 3. My Insight has Silver colored buttons. It has the date 03/06 on the side of the unit next to the S/N.
After I connect the Insight to my PC, and open the Sherwood software, I click on Dives and am prompted to add Dives. I select Import from my Insight, and the Import Dialog opens. It says USB interface FOUND. I then click the "Play" button to begin the download. It then says "Starting Handshake..." briefly, then says "Time Out." and closes the window.
If I click on the File menu and Select RUThere, it tells me the "Unit if OFF" even though the Unit is on. It does this regardless of the device being in EA mode or not. I have tried the cable on 4 different USB ports on my PC.