Hi mate, welcome to the forum
It could be a number of things...
1. Could be down to your modchip & booting method, check them out
here
2. Could be down to the media you have used. Monarch? Try some better quality such as Traxdata or Ritek (search on this forum for those two for more info)
3. Could possibly be down to the Auto Insert Notification setting, check out how to switch it off
here
Give these three a try, any further problems then shout