windows 7 - Websockets connect but fail to send messages

This is a maddening problem I come across once or twice every few months: websockets aren't working right. Here's the facts:

1. My browser can connect to my local (loopback) server, but when the browser sends messages, the server never gets them.
2. This has happened a few times to me before in the last 6 months - it always seems to start working without any change on my end, and for no apparent reason
3. Most recently, this started happening right after I restarted my computer...
4. http://www.websocket.org/echo.html also doesn't work
   • The connection is being closed with code 1006, wasClean is false, and reason is a blank string
5. Websockets used on trello.com do work for god knows what reason
6. Firefox and chrome both have this problem
7. I've confirmed that turning off my firewall (windows 7) doesn't change anything
8. I've also confirmed that a node.js client and server works on linux (centos 6 VM running inside my windows machine), but the same client and server setup doesn't work on my windows machine (tho when I tested on a different windows 7 machine, it works fine)
9. I don't have antivirus software running, so that can't be the issue.

Here's the info from chrome's network tab:

Request URL:ws://echo.websocket.org/?encoding=text
Request Method:GET
Status Code:101 Web Socket Protocol Handshake

Request Headers CAUTION: Provisional headers are shown.
Cache-Control:no-cache
Connection:Upgrade
Cookie:__utma=9925811.1690403310.1402691326.1402691326.1402691326.1; __utmb=9925811.13.10.1402691326; __utmc=9925811; __utmz=9925811.1402691326.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
Host:echo.websocket.org
Origin:http://www.websocket.org
Pragma:no-cache
Sec-WebSocket-Extensions:permessage-deflate; client_max_window_bits, x-webkit-deflate-frame
Sec-WebSocket-Key:eH9OcxKQ/I6S+IkzY+HsaA==
Sec-WebSocket-Version:13
Upgrade:websocket
User-Agent:Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.131 Safari/537.36
Query String Parametersview sourceview URL encoded
encoding:text

Response Headers
Access-Control-Allow-Credentials:true
Access-Control-Allow-Headers:x-websocket-protocol
Access-Control-Allow-Headers:x-websocket-version
Access-Control-Allow-Headers:x-websocket-extensions
Access-Control-Allow-Headers:authorization
Access-Control-Allow-Headers:content-type
Access-Control-Allow-Origin:http://www.websocket.org
Connection:Upgrade
Date:Fri, 13 Jun 2014 21:36:59 GMT
Sec-WebSocket-Accept:d0eOTUUxMpkKsI6x9RJ+vGBxl3w=
Server:Kaazing Gateway
Upgrade:WebSocket

Is there something that looks wrong in those headers? Anyone have any idea what might be going on? Its like my computer is blocking websocket messages but not connections.