I have experienced the same issue and for the longest time I was unsuccessful getting my Ubuntu to work like my Hyper-V 2008 R2 RDP to Win7, Win8 worked. In fact, I was so MS over the whole thing I never thought I'd get my Tablet using aRDP to connect with my RDP Services running on Server 2008 R2.
But, thanks to this post and several others I put together my simple guide to MS people going Ubuntu.
Required reading: You probably also know that since the introduction of Unity Desktop Interface in Ubuntu you need to tweak the configuration in order to have it working. The most annoying part while using xrdp (with Ubuntu) is the fact that you have to install an alternate desktop environment.
Loaded up Ubuntu 14.04 following the instructions from Griffon's IT Library then the magical line in terminal
to open gedit in root edit mode
make the changes as suggested in the link Ubuntu 14.04 LTS xrdp grey screen and you now have something to work with.
THE FIX: edit /etc/xrdp/startwm.sh (as grahaml44 wrote)
Thanks grahaml44 for that fix.
Score one for those that know!
Now for Round two, I'm not done, we're finally getting things working. Let's push it to make 4 VM's in less that 20 minutes work remotely. I have an addiction with my tablet to switch desktops very often while in the company of iPad users.
Using Griffon's IT Library once again (almost have an IT Crush) we find ourselves following yet other Ask Ubuntu members (Thanks again!!).
ubuntu 14.04 xrdp grey it was the post by "Nobody" and "abrasadera"
If you look at what Eric Gosh posted you'll see that the gnome-session just isn't going to work. I agree and my attempts which all failed confirm it.
So there you have it, two methods 100% Yes they work and verified by so many others and "Me".
What did you expect? Someone from Microsoft?
I've noticed you can create multiple sessions. I think I'm going to need a bigger server now.