This is a bug which I'm not sure has officially been reported. With the new EB13 FROYO when you go into task manager then ram manager and do a level 2 ram clear, it shuts down a critical SMS process that I've found won't correct itself until reboot. I'll try the airplane toggle to see if that works but I thought I had tried that already.
Anybody know how to officially report this as a bug? I know of several people who can confirm this as an actual bug.