MemoryTab is greyed (disabled) when a previous connection terminates.
I'm not able to consistently reproduce the problem. It could
be related to timing.
I was able to reproduce the problem a few times with the following steps
but not always:
1) connect to one JVM
2) select the memory tab
3) kill the JVM being monitored while jconsole is connecting to it
4) when the connect dialog box is displayed, start running another JVM
5) connect to the new running JVM
The MemoryTab is greyed in color and MBeansTab is the first display.