Lync 2013 - blank desktop after accepting a Desktop sharing request

Someone wanted to share their desktop with me using Lync 2013. Everything looks fine, I accepted the request, the Lync window grew larger but my colleague's desktop was not there! There was just a blank white space. The colleague sharing their desktop with me did not realise anything was wrong. Why can I not see their desktop?

Solution
I searched on the web and read a few articles and forum messages. It seems to be a problem with object security and you need to remove a registry key to fix this. I found this article:
http://blogs.technet.com/b/lync_tips_and_tricks/archive/2013/01/11/lync-2013-desktop-sharing-shows-blank-screen.aspx

It has fixed the problem for me. Here are the steps I took:

NOTE1: You must have Administration access permission for Windows.
NOTE2: My example is using Windows 8.1 64-bit and Lync 2013 32-bit.

First start the Event Viewer and look for the Office 2013 alerts, there will be one generated from your attempt to use Lync's desktop sharing - here's how:

Press Windows key and R to bring up the Run dialogue box
Enter eventvwr and press Enter
Expand the Application and Services Logs section

Click Microsoft Office Alerts - see the screen shot below...

In the above screen shot, you'll see I had an alert at 10:23. I clicked on it and in the space below it lists some information. The interesting part is the CLSID number - note this! In my case it's a whole string of zeros.

Start Regedit (press Windows key and R, enter regedit)

Browse the tree to:
HKEY_LOCAL_MACHINE
SOFTWARE
Wow6432Node
Microsoft
Internet Explorer
ActiveX Compatibility

Select the folder that is named the same as the CLSID number you saw in the Event Viewer - in my case the one with just zeros.

BACKUP: Click File | Export  - save a copy of this registry entry as a backup. If later you decide this didn't help or there's some problem, you can restore it.

Delete the key Compatibility Flags

Now ask someone to connect with you and share their desktop - hopefully it should work!


Conclusion
This is a strange problem and I wonder if Microsoft will roll out a fix for it at some point? From what I can understand it looks like an ActiveX component is blocked. I read on a forum that one person said they could get around the problem by using Firefox as their default browser. Presumably Lync would us Firefox to render the shared desktop rather than IE, as Firefox doesn't use ActiveX then there would be no security issue? I also believe from what I've read that this issue only affects Lync 2013, since there was an update to security for it. Lync 2010 users may not have this problem at all. Whatever the reason for this, I hope that Microsoft fixes it properly at some point. I'll be watching my PC carefully to see whether this issue comes back - after all, I don't know why it happened in the first place, I was previously using Lync 2013 desktop sharing without a problem.

If/when I discover more about this issue I'll update this blog article. In the meantime, feel free to write your experiences in the comments.


Reference
As mentioned above, I found this here:
http://blogs.technet.com/b/lync_tips_and_tricks/archive/2013/01/11/lync-2013-desktop-sharing-shows-blank-screen.aspx (last accessed 22/09/2014)
Many thanks to Joao Loureiro for this.

Also explained here:
http://lyncuc.blogspot.ch/2014/07/lync-2013-client-desktop-sharing-show.html (last accessed 25/08/2016)