Don't set RootFolder *and* SelectedPath, or be more careful when doing so. They're related to each other, and by setting them both you make it impossible to achieve your goal.

RootFolder is "the root folder where browsing starts from". This, in fact, can restrict what appears in the dialog. For example, if I pick Program Files, you'll ONLY be able to see folders that are inside Program Files with the dialog.

SelectedPath is more or less "the folder that is currently selected". It isn't guaranteed to be on the screen, and may not even be valid.

So if I set RootFolder to "Program Files", but set SelectedPath to "C:\Windows", what happens is I get a FolderBrowserDialog that is rooted at "C:\Program Files" but has no visible selection. If I dismiss it without selecting a folder, SelectedValue will STILL be "C:\Windows", but if I select anything it will have changed.

You can't see network paths because they are not located under "My Computer" in the hierarchy. This sort of makes sense, in that folders with paths like that usually exist on OTHER computers. When you set SelectedPath, the network location can't be displayed since it's in a different hierarchy, so it looks like it's broken.

So you need to set RootFolder to something that can display network locations, and the only one I can find is "Desktop". My guess is if you do that (or just let it stay at the default value, which is "Desktop") you'll have more success.

As for scrolling it into view, it looks like that is fairly involved and requires some API calls because someone in Microsoft was asleep at the wheel when designing the behavior.