Applications Flashing Between Monitors

[Sean Perryman1709158861]

During the deployment of a new Citrix XenApp 7 environment (Windows Server 2012 R2 for both VDA and StoreFront), there has been a strange issue that was nearly impossible to replicate. Sometimes users would call and say their applications were flashing back and forth with a black screen. Upon remoting into their machine I can see that is the case. The only fix I found to get them working again was to log them out and back in, which worked 100% of the time at the cost of them losing any unsaved work. Here is a video of the issue to which I am referring:

 

Citrix XenApp 7 Flashing Issue

 

After researching various fixes and causes it seems to be something to do with monitor resolution and/or changing the DPI (Make text larger or smaller in Display Settings) on Windows 7 specifically. I am unable to replicate the issue on my Windows 10 desktop, but on Windows 7 here was the process that seemed to cause the issue consistently:

 

Log in at one DPI setting 

Launch XA and a couple of published applications

On the desktop machine change the DPI setting and log out without logging your self out of your XA session

Log back into the machine and launch a published application

This should reconnect your session, and the black screen flashing should begin

 

I tried going back to my Windows 10 machine with a flashing black session and reconnecting, but the flashing continued. My initial thought was the DPI was the issue, but upon checking the PC of a user experiencing this issue multiple times, everything is set to the default Windows setting (Text Smaller, 100% text-scale). 

[Sean Perryman1709158861]

I can't imagine I am the only one who has ever had this issue before. Perhaps the only one who has posted it here? 

[Umesh Patel]

You are not the only one seeing this issue. We have recently started to struggle with this especially because we are having to set DPI on Server 2008 R2 for a specific application and this flashing issue between monitors is primarily happening for us on Windows 10 clients. With Windows 7, it was easy to set DPI on the client which matched the DPI enforcement for the application on the server so we never saw the problem there. We have not yet found anything that has helped the situation for our colleagues that have upgraded to Windows 10. Will update this post if we find anything from our triage.

[Forrest Blair]

Have the user unplug and then reattach the second monitor.  Fixes it every time.