It was only a matter of time before Justin would get some crazy stalker coming at him during his stay at the Montage Resort Laguna Beach. Biebs owns a residence there and he and Hailey have been enjoying the beach, the pool, the main lawn, the spa -- all the resort's amenities. But they're literally in the middle of a whole bunch of tourists who are also staying at the hotel and the random LA-area fans who drive down to Laguna to stalk their favorite pop star.

Well one such fan got waaaay outta control Tuesday when she entered Justin's suite. Bieber told her to get out and then his security took it from there. Hailey was up in Los Angeles for some modeling duties, so she wasn't around to witness the scary event. The 30-year-old woman was arrested for being drunk and disorderly and for trespassing.

The whole event came just hours after Justin posted a serious message to rabid fans on social media -- BACK OFF! He said he's tired of the negative element being mean to Hailey on social media and saying that he'd still be with Selena Gomez if it weren't for her. He said it's just not true -- that while he'll always love Selena, Hailey's his wife and his full-time focus.

Perhaps this lady didn't get the memo?

Moments after the incident, after cops whisked the woman away, Justin went out onto his balcony to take in the view of beautiful Laguna Beach. Presumably he'll be leaving the residence soon, when he and Hailey move in to the new Beverly Hills mansion they recently purchased. We hope he'll have better security there!