How to deal with a player that interrupts play?

As mentioned here, I started running a full blown campaign of The Dark Eye after about 4 or 5 sessions to make characters and learn the basic rules with a low impact preliminary adventure set around Greifenfurt in 1009 BF, before all the debacle of the third Ork invasion. Up to that saturday, I had to fight more with the player with ADS – let’s call him Adam – to keep the attention at the table and let me finish my sentences, but he did pull himself together most of the time and warned me when he needed a short timeout from lengthy telling .

On that saturday, one of the players – let’s call her Berta – did start with a pretty new behavior she didn’t show before: just about every time i was about to tell something about the situations they find themselves in the Battle on the Silkwiesen (an atrocitiy of scipted 15 page scene – more here, abberated there), Berta asked something either trivial or otherwise derailed concentration. Atop that, she breeched the table contract blatantlysee below. Rule questions were not an issiue, as all are pretty new, I do explain the rules regularily on request. Some examples:

  • Berta out of nothing started talking about Pok√©mon, resulting in a derailment for about 15 minutes until we could return to the game
  • Despite cellphone ban at the table, she did pull hers out to text somebody.
  • When I used “Haufen” – a description for a small group of people (~mob) or pile/heap of items – she started to giggle maniacly, as she thought I was talking about a pile of excrements.
  • For just about every term she didn’t know, she asked for an explanation there and then by interrupting. Normally I am very lenient and explain those words on request or try to make them clear out of context, but I dislike very much being interrupted for it. Some of the words she asked to have explained were not that uncommon.
    • The first… couple incursions I did answer the question, then went back to trying to repeat the narrative from where she interrupted me. Later in the evening I got a bit harsher in tone, telling her “In a moment. Let me finish this passage first.”
    • She did appologize for this behavior on sunday.
  • About 10 or more times she asked me to repeat something a NPC did say. After the 4th time (or such) I ruled: “If you didn’t catch it, your character didn’t catch it. Keep your head at the table please.”

As noted, this behavior is new for her, before she did wait for her turn to ask, and kept her talking at the table/in the game. I did – in contrast to the sessions before – not repeat the table contract before starting.

Our table contract

  1. Nobody may interrupt another player verbally or demand silence but the GM
  2. No cellphones but for checking time or emergency. Only calls are emergencies.
  3. In case of squickgore, erotic, whatever, make a Timeout-T with the hands, and the player/GM shall stop.

Question

What type of problem player I deal with here and how should I address the issiue?