Cant see why this JavaScript-code won't run - settimeout

Question

I'm new to JavaScript and have written this code. It worked before, but now it just don't, and I don't understand why. The text on the button doesn't even change to "PAUSE". When I try it in the browser it says after a while that "localhost is not responding due to a long-running script."
<div>
<div id="tabataBox">
<p id="PauseGoText"></p>
<p id="stopwatch">CLICK TO START WORKOUT</p>
<button id="tabataButton" onclick="startPause()">START</button>
</div>
<span class="circle" id="el-1"></span>
<span class="circle" id="el-2"></span>
<span class="circle" id="el-2"></span>
<span class="circle" id="el-3"></span>
<span class="circle" id="el-4"></span>
<span class="circle" id="el-5"></span>
<span class="circle" id="el-6"></span>
<span class="circle" id="el-7"></span>
<span class="circle" id="el-8"></span>
</div>
</div>
var time = 0;
var running = 0;
var everySecond = true;
var max = 20;
var numberOfTimes = 1;
function startPause() {
if (running == 0) {
running = 1;
document.getElementById("tabataButton").innerHTML = "PAUSE";
increment();
}
else {
running = 0;
document.getElementById("tabataButton").innerHTML = "START";
}
}
function reset() {
time = 1;
document.getElementById("stopwatch").innerHTML = "0";
if (everySecond == true)
{
everySecond = false;
max = 20;
document.getElementById("tabataBox").style.backgroundColor = "green";
document.getElementById('el-'+numberOfTimes).style.backgroundColor = "green";
numberOfTimes++;
document.getElementById("PauseGoText").innerHTML = "REST";
}
else {
everySecond = true;
max = 10;
document.getElementById("tabataBox").style.backgroundColor = "red";
document.getElementById("PauseGoText").innerHTML = "GO!";
}
}
function increment() {
if (running == 1) {
setTimeout(function () {
time++;
if (time > max) {
reset();
}
document.getElementById("stopwatch").innerHTML = time;
increment();
}, 1000)
}
}