Compiling Media Library... happens if WDTV LIVE HUB finds new files in order to do content aggregation, The speed at which this takes place depends on how fast your NAS share is and also how many files you have on the folder you have shared on the network, The new firmware requires that you have your network share in READ/WRITE mode so that it can create .wd-tv folder, and create thumb files for all the image files etc; etc;
If the unit is always displaying "Compiling Media Library..." it means it never finished the content aggregation process of the files and folder that it found.
In order to troubleshoot this, Please stop your network share and see if the WDTVLIVE HUB can finish the content aggregation of the internal HDD first, That also depends on how much files you have loaded on the internal drives but usually seen to complete in less than 30 mins, If you really want you can also clear the Media Library and let it re-compile for the internal HDD and let it finish the content aggregation process
Once you are sure that WDTV LIVE HUB has stopped displaying the "Compiling Media Library..." you can be sure that nothing else other than the speed and the sheer content of your NAS share is the cause of this constant "Compiling Media Library..." issue.
If you power-off the unit completely either by pulling the plug or pressing the power button on the front panel or remote for more than 3-4 secs it will completely shutdown the unit and it will have to re-compile the databases again.
I agree your frustration my friend, but that is how it is designed, It does not keep track of the list of known files it aggregated the first time, it always find the files and re-compiles again and again when resumes from a full power-off. This unit is not designed to be turned off as it was designed to be a NAS server also.
When the Compiling Media Library... is displayed the unit can be used, It play movies, browse the online services just certain features like getting content metadata information is not available...
Hope this helps
With best wishes