A few observations:
1. If I turn the gateway on first, then I get an "ok" on the node on its first packet.
2. However, if I turn the node on first, the gateway still receives the packet, but the node does not receive an ACK
3. If I leave the node running and reset the gateway, it can read one packet before hanging
4. The 'r' radio.readAllRegs() command will cause both gateway and node to hang.
5. Switching the node/gateway Motes gives the same result, so it doesn't seem to be a hardware issue with one of them.
6. The struct_send/struct_receive sketches have a similar behavior.
7. If I set the frequency to 433 on purpose, I still get the first "ok". So maybe that "ok" isn't real?