The upgrade to 4.55 or later can be difficult on SunEyes that shipped with the original OS installed (device software version 4.40 or earlier). We have been unable to resolve the occasional difficulty upgrading the device OS. It requires that the firewall be turned off and it may potentially work on any Windows OS. It may potentially fail on any Windows OS as well. We have found that the failures happen most often on PCs that have AMD processors. The exception are AMD based computers running Windows XP. Intel processors succeed more often with any Windows OS. You may need to reset the device as per the on-screen instructions during the installation. I would try it at least 2 times with the firewall off (it will never work with it on) before cancelling the installation. Reattempting the installation on another computer with a different hardware/OS configuration is the only workaround. It would be good if you can locate a machine in your office that will complete the upgrade. Performance is consistent. If it works once it should always work for any device, if it fails more than 2 times consecutively it will probably never work on any device.