I have found the same problem. When Spark is running cannot RUNAS into MMC - Microsoft Management Console. We are network sysadmins and use Spark to communicate with each other across the WAN. Therefore we need to run “mmc dsa.msc” using an administrative Windows account to manage the Win2k Servers and User Accounts, etc.
Problem occurs as far back as version 2.4.1 and up. Version 2.0.8 does not have the problem. Whenever Spark is logged in to the Wildfire server it hangs the MMC which stops responding. As soon as Spark is logged off or exited the MMC immediately starts responding again. There is some sort of conflict.
Uninstalling and reverting to Spark 2.0.8 causes the problem to stop occurring. Unfortunately, I don’'t have time to do a debug thread trace or memory dump of mmc.exe and/or Spark.
You don’'t even need to have Win2k server tools to make it happen. It happens just performing a RUNAS with another domain account when launching MMC. Even with no plugins it starts clocking and not responding with the hourglass if Spark 2.4.1+ is running.
Two of us were running the betas of Spark. One 2.4.1 and another 2.5.1 Beta 2 and we both had the problem. Found others reporting problems with Spark 2.5.1 Beta 3 on this thread. Hence my two cents worth.
Could it possibly be an issue with Java 1.6 JRE? All of our Spark installs used the included JRE and did not rely on an existing JRE.