ActionScript 3.0 :: Data Limit To Sockets - Events Stop Firing

I have a pretty elaborate class that extends Socket and performs some serialization and data protocol stuff. It works pretty well when I send small messages. However, when I send anything over about 132KB at once, the SOCKET_DATA progress events stop firing -- or at least the function I've got listening for them does. My class is called RPCSocket and I assign the socketDataHandler function like this in my constructor:
addEventListener(ProgressEvent.SOCKET_DATA, socketDataHandler);

My socketDataHandler function (with lots of comments) is attached. Is there some limit to how much data can be sent over a socket at once? Is there something wrong with my code? Here's the trace output:
Code:
socketdatahandler
bytesAvail:4380
buffer length:0
reading bytes into buffer for concat
buffer length after concat:4380
buffer state:0
[Code] .....