I don't know the cause, or a proper cure. but...
<OnTimer type="random" interval="300">Will cause the bot to say something random on a 5 minute cycle, & therefore you'll never see inactivity for 6 minutes.... I'd recommend LOTS of random output lines or it'll get boring.
// Add as many output lines as you wish
<out>/me pokes the room</out>
<out>/me says something just to move the screen</out>
<out>∗Tickles all the lurkers∗</out>
*Edit typo in the word ' interval ' corrected BB