I think that the problem isn't related to the registering of dll with installer. I tried manual registering and all was the same. Also, in versions 0.8 and 0.9 beta different installers are used, but the problem is present in both versions. Seems that the problem is caused by some conflict between the actual dll and Windows and due that problem some Registry entries were not stored. Also, seems obvious that such problem isn't present on all versions of Windows. Usually, I don't have such problem with other applications (maybe only with context menu plugin of FreshView, it also doesn't appear). With ShelFTP 0.71 all still works fine (I tried to install it again), so you can trace the problem because you know where is the important difference between v.071 dll and actual version of context menu dll. Maybe a workaround is that the main executable make a registry query upon start and if some important keys aren't present write them in the Registry.
Related to "Cannot draw on canvas"... I think so, not sure because now I have installed v0.8, but after the error there were also several application crashes. I'll try to install it again and then report to you.