Strange behavior loading/unloading VIs in a subpanel

[Drouilhet]

Hi all,

I have an application in which the user interface has a subpanel which can display many different VI front panels, one at a time. The user selects which VI to load into the subpanel using a combination of radio buttons. I have developed this application over many years, and until recently the subpanel has been operating as desired. Sometime over the last several months, it has developed a strange behavior. If the main HMI VI is loaded in the subpanel AND the HMI has been idle (no user interaction) for some unknown period of time (minutes or hours), when the user selects a different VI to load (by changing the radio button selection), the whole HMI VI (and possibly all the VIs operating in the background) freeze. LabVIEW doesn't outright crash, but I get the spinning "busy" symbol on the the screen, and it is no longer possible to interact with the application. After some period of time, which can be 30 seconds to 20 minutes, the display unfreezes and LabVIEW resumes normal operation. I am pretty sure this only happens in the built version of the application, not in the development environment.

I am mystified, because I don't believe any changes have been made to the code that loads and unloads VIs from the subpanel. And it seems to only happen when unloading one particular VI from the subpanel and replacing it with another. It doesn't happen when navigating away from any of the other 30-40 VIs that can be displayed in the subpanel.  Any thoughts on the cause or best methods to diagnose this behavior would be most welcome.

[LesHammer]

Question: Is it just LabVIEW or do other applications also freeze?  Some unnamed software company may be trying to encourage people to update to Windows 11 by making old OS versions freeze at random times.  I would put a just kidding smiley face on this, but I've noticed that my W-10 computer freezes occasionally - not running LV at the time.

[Drouilhet]

I wish it were that simple. It is only LabVIEW that freezes. And the writers thing is that is I wait long enough, it unfreezes and goes on its merry way.

[LesHammer]

Did it start acting strangely after a modification or was it working fine for months and then started acting up?  (Searching for a cause.)  Is there an uninitialized variable that is "0" when in the development stage but is now random and on a count-down from FFFFFFFF that takes 30 minutes to process?