Alarm system is alarming!

[lowcost]

My wife's 2000 model Corolla woke us up at 6am this morning. The alarm was wailing like a banshee. I got up but it had stopped before I got downstairs. As I started back the alarm sounded again. I reset it with the remote but it kept starting up after I had reset it. I left the car unlocked and it was OK.
Now we can only lock the car, without the alarm going off, by turning the key in the lock. Using the remote makes the alarm sound.
When we unlock the car with the remote the alarm makes quiet bleeps for 20 seconds or so then stops bleeping. Is it trying to tell us something?
This all started when the electric windows failed. I checked all the fuses then noticed that a switch on the drivers door had been pressed. I unpressed it and the electric windows worked. Later that day.... at 6am to be precise, the alarm decided to annoy us.
What happened? Is it something we said or was it something I did?

[01loadedLE]

try turning the motion sensor down under the dash it may be set way too sensitive. thats what I had to do to get ours to stop going off all the time.

[karazy]

It does sound like something is wrong with the system.

Warning A favorite SOP of some SOBs is to activate the alarm until you turn it off, so they can break into the car.

[lowcost]

Thanks for the two bits of advice gentlemen

(1) Where is the sensitivity control exactly?

(2) When the alarm keeps going off I'd gladly give the car away!

Sometimes when you lock it with the remote it's OK for hours but other times it goes off almost right away. I wondered whether a mouse inside the car would trigger the sensor?

A clue may be the quiet beeping sound it makes for 20 seconds or so when the door is opened?
My wife reckons she remembers something about this but can't say exactly what.

[01loadedLE]

the sensor should be under the drivers side dash. I had to turn mine almost all the way down before it stopped going off. toyota told me they've had alot of problems with those sensors and that they were considering switching brands. now I dont have problems with it and it still activates when the car is tampered with so lower the setting and it should work fine.

[lowcost]

The alarm system is working again

From the history I think the LH rear door switch must have been intermittent

We don't use this door much and after I'd given a lift to a friend who used the LH door the drivers' door could be opened after unlocking with the remote without any accompanying beeping

Now we can set the alarm and it doesn't go off after a minute

Presumably the door switches get dusty when they're not used much

Moral is to open and close all the doors a few times every so often

It must be like a crackly volume control on an amp. This happens when you don't change the setting for a very long time