Restart NetworkManager after you force quit in long standing RHEL

I notice that sometimes if my rhel desktop is going for a while, and I do alot of weird stuff to it, I have to force quit "NetworkManager".  Then, the wireless connection can drop out. 

And then... when I try to restart networking, I got this error:

bringing up interface eth0: Error: Connection activation Failed: networkmanager or unavailable

After looking at some posts, the consensus was "don't rely on NM for everything".  

I think essentially the trick, then, is to get networking back working again, without NetworkManager, and THEN turn NetworkManager back on. 

This is totally phenomenological I have no idea why it works, but maybe someone can post a comment about why this seemed to fix networking for me on my box:

1) Edit this file: Set "NM_CONTROLLED=no"

vim /etc/sysconfig/network-scripts/ifcfg-wlan0 

2) Now, this command should get a little further than it did before you ran into  
service NetworkManager stop
service network restart

3) Then, you can restart NetworkManager if you like using it:
service NetworkManager start

And again all is right in the world.   So, although NetworkManager is convenient to set stuff up with, I guess after all you don't really need to run it once your networks are stable.