Yes, I have this problem since going to 148. Not only do my contacts show as unreachable, but I notice that it is taking linger for my messages to send when this is happening.
I am also noticing much lower free memory as everyone in this thread. Phone is working fine, but wtf...... this was an upgrade ? To be honest, i dont see much difference from 75 in terms of lag issues. So far, my messenger and memory was way better on 75.