Hi, we have the product package so we get autocad Mechanical. We actually use the vanilla autocad though. On installing people couldn't dblClick a dwg in windows explorer to open it. I know 2019 only has sdi=0 but I that doesn't matter, I just wanted users to be able to open another dwg (be it in the same running autocad) by dblclicking. Part of the problem was solved when I realized that the IT guy hadn't opened Inventor on every machine (If it isn't opened once it doesn't register and messes things up). So now if cad is not open and you dblclick a dwg it opens cad and the dwg and allows you to dblclick open other files. If you open cad with the icon the dblclick doesn't work on all machines. Some are win 7 and some are win 10 but that doesn't seem to matter. I have win 10 and sometimes I can dblclick open and sometimes not. Very confusing.