Despite the error message, I'm not sure that there's actually a problem with communicating with the Team Server. Could you try downloading the project again from the Team Server? To do this, please go to the 'Project' main menu, select 'More Versioning -> Download from Version Control Server', and then make sure that you download the project to a new location on your disk.
If this works, then you should be able to work with the newly downloaded project, and there might be something wrong with the copy that was already present on disk.
No still the same, as soon as I choose app and click OK, that message appears.
Ok, I've managed to get it running on laptop, however two PC's still refuse to do so, so it's a PC problem, something with network settings, but I don't know what.
I happens to me always, but even so it gets updated after I press "run". Have you tried that?
I see this post ist a little bi old, but I had the same problem, and I resolved it.
For me the problem was that I had automatically created workspace on my company virtual disk. Than I wasn´t be able to open my project with the Desktop Modeler. After I changed workspace and created new map on my C Disk, now it works without any problems.