Law enforcement sources tell us, someone broke into the singer's Beverly Hills-area home mid-morning Friday. The intruder got in by smashing a bedroom window.

We're told the house was "ransacked." The burglar/burglars made off with music equipment and personal property. Our sources say among the items taken ... some of John's watches. He has an enormous and enormously valuable timepiece collection.

Our sources say the value of the property taken is between $100,000 and $200,000.

No one was home at the time of the break-in. We don't know if John's burglar alarm was on.

Somewhere around noon, a security guard noticed the broken window and called police.