Alarm when doors unlocked

[hilmia3]

2000 Sienna XLE

When the doors are unlocked, either remote or by key, the alarm goes off (poor neighbors at 6:30am!) and will not stop until the key is inserted into the ignition. This has been going on for a couple days; nothing was done mechanically to the car recently. The alarm came with the car; it's not aftermarket.

I've looked through all the forum and found nothing about this. Any help/ideas would be much appreciated, thanks!

[Black Sunshine]

Is it actually going off when unlocked or opened? Either way it's because it's not disarming as it should.

[hilmia3]

When unlocked, annoyingly enough.

If it's not disarming properly, is there anything I can do to fix it?