I have found the time to do some debugging on the issues with the recent firmware updates (302 & 310) that are causing widespread issues.
I will leave aside the obvious comments that USERS should NOT be having to DEBUG this software, and that WD should allow us to roll-back the firmware as a matter of course.
Using SSH I have been able to monitor behaviour of the unit when various events take place. I have noticed that TWONKY seems to be the main culprit (in my case). When I am not accessing the unit via the GUI, but only via SSH, twonky behaves itself and the unit is mostly idle. However when connected to the GUI via a browser, twonky sparks up and reliably grabs every bit of CPU resource going (with the help of wdnotifier). If I log-off the GUI, twonky goes back into quiet mode. In this state the GUI is very slow, and the unit is thrashing its disks. I would note that the EX4 has a USB drive attached, although this is also set for no media scanning (via the twonky GUI and the EX4 GUI).
I am not actively media sharing, I have turned off all scanning of directories.
When I kill twonky, the EX4 comes back to life, but the GUI no longer allows a logon. I cannot understand why twonky is associated with the GUI.
Anyone have any ideas?