I just bought a new 436HP and am trying to install Sentinel software so I can update the Firmware. You cannot do it using ARC software from Butel. I use Butel software on all of my scanners. I run "Setup" only to receive a message saying I need Microsoft Net Framework version 2 installed. I've done this several times to no avail. I get a message saying there isn't enough space to unzip and install when in fact there's plenty of space available. I even tried downloading the software only to get the Net Framework error message. I've never had this problem with Uniden or Butel. I rarely need help and I'm begging for it this time. In the meantime I'm editing my scan lists with ARC software. Even this version of ARC is a little bit hard to understand and use.