Mine used to hang up, but not anymore.
My neighbor to the East interferes with all 2.45GHz devices.
When I moved my A+ to the other side of the house, it's been stable.
Aside from that, it's important to make sure your A+ isn't overheating.
Lots of vents, but if it gets no airflow, it will become unstable.
Not an A+ thing specifically - all embedded systems.
Wall-mounting on an inside wall is best, because it will create its own airflow as the heat rises.
In a sunny window is worst.