IRC-chats disconnects frequently when chat inactive

[Zeph]

I'm trying to help a friend who's having trouble with IRC-chats on her laptop.

The problem: Whenever she uses IRC-chats and there is low activity in the chat (eg. 1-5 posts a minute), she disconnects. She only uses Twitch.tv regularly (game streaming website), which is where the problem occurs.

Additional info:

• It's a laptop, about 1 year old, running Windows 8.1, connected with wifi, always plugged in with the charger.
• She's been having these problems for months, even since starting to use twitch.tv.It happens on home network with wifi and at work network with cable. I know some work networks blocks IRC, but channels with more activity works as they should.
• I did some testing, and it only happens when the chat activity is low, but she doesn't have to post anything personally. We went to my channel on Twitch, only the two of us, and I posted something every other second for 10 minutes, she never posted anything. During this period, she never disconnected. Then I stopped posting, and she disconnected after a few minutes.
• In larger chats (300+ viewers), where the chat activity is higher, she does not disconnect. It is only a problem in chats with low number of viewers where the chat doesn't run as fast.
• No other Internet services are affected. She can view streams, stream herself, use Skype and everything without issues. The problem persists, regardless of Internet traffic on her end. IRC is the only service/application that acts like this.
• I opened a chat on tinychat.com and she joined. After a few minutes, she disconnected.
• She's tried using different browsers, a chat client called Chatty (for Twitch) and mIRC (Twitch server setup). All experience the same problem. In mIRC, she got the 10053 error, which I understand can have lots of causes and doesn't tell you a whole lot.
• Thousands of people use Twitch every day without problems. I can find a some comments on support forums from people which are having the same problem, but haven't found much in terms of answers or solutions.

Example log from mIRC:
I've replaced her username with "username". I'm not sure how accurate the timestamps are, since I sometimes see her leaving, then see her posting something before the rejoin message pops up a bit later. But she seems to disconnect after 2-5 minutes all the time.

[20:05:02] * @username (username@username.tmi.twitch.tv) has left #username
[20:05:02] * jtv sets mode: -o username
[20:06:00] * username (username@username.tmi.twitch.tv) has joined #username
[20:06:00] * jtv sets mode: +o username
[20:06:58] * @username (username@username.tmi.twitch.tv) has left #username
[20:06:58] * jtv sets mode: -o username
[20:09:08] * username (username@username.tmi.twitch.tv) has joined #username
[20:09:08] * jtv sets mode: +o username