Okay... This should not be too dificult... I am a computer helpdesk technician for a Capital City. Let me ask, is the stinger connected via a USB interface cable or a serial cable? If a USB cable, then you should not get "device not found". Have you tried different USB ports on the PC (if using a USB cable)?... If so, and you still get the error, then I would delete the driver for this device and let Windows try to find it again. First, however, In Dive manager software, I would try COM3... My Helo2 works on Com3 by default. If still a problem, you need to find the device that is recognized by windows when you plug in the device and select the PC interface protocol on the stinger, regardless of having the manager program open. Go to computer, right click and select manage. In the new window, find device manager and find the entry that represents the stinger, (maybe under ports). It should be something that shows up when you plug in the cable and disapears when you unplug the cable from the PC. Double click that item and uninstall it, unless it is under a com port other than COM1. Replug to let windows try to reinstall it. If for instance, it was found under COM2, then you need only select COM2 in the Dive Manager software... Let me know how it turns out.