Cannot retrieve nodes

[simplextech]

 

I've gotten this error message a few times lately.  Any ideas what could be causing this?  I just had a program fail to run which has also been happening a couple times a week (same program).  This time I checked mobilinc and it showed the door was open but the lights did not turn on.  I came back to my desk to load the Admin Console and I'm welcomed by this when I try to logon to the ISY.  Trying again and everything loads like normal.