I am using Robohelp 9, but will be migrating to RH11. In both cases, when I navigate in Robohelp to the folder that contains my Robohelp project, I can see folders, but the files in the project do not appear. The files do appear for one of my associates on her computer. Also, the various RH projects do not appear as they do on hers.
For my money. the simplest way to see the folder and files is to right-click on a file in the Project Manager and choose "Explore". That should drop you into Windows Explorer right there at the location your project is. If you have done this and you don't see any files, you likely need to tweak the Windows Explorer application by clicking Organize > Folder and Search Options > View tab. There are options there that govern what Windows will show you.
Personally, I have mine set as follows:
See if making those changes seems to help.
Sorry if I was a bit foggy in my explanation; the problem is I can't open a project, as they do not appear in my Robohelp Recent Projects window, whereas they do appear there on my colleague's computer. Even when I navigate to the location on the server where they are located, they don't show up.
(side note: I personally wouldn't work on a Robohelp project over the network - theoretically it is now possible, but I've never had a good experience with it. If you have Source Control (TFS, subversion, etc) then that is fine, as when you Get Latest Files that will copy the files to your local computer.)
Regarding not being able to see the projects, perhaps check the Files of type field in the Open dialog box. Perhaps it is set to something like Winhelp File, which I assume you aren't using. Make sure All Help Projects is selected, so you can see the Robohelp xpj files (I've done this a few times - never have figured out how I managed to change the selection).