2000 A4 1.8L Turbo - Alarm Problem

Hi all, I'm hoping someone can assist me with what has become a rather annoying fault on my old girl that started Saturday.

When I unlock the car, the alarm beep beep beep beep kicks in.
First happened on Saturday and when I locked and re-unlocked it stopped.

This morning though, did that, then when I started the car the beeping started again.
Had to lock, unluck, start, turn off etc a few times before it stayed off. Very annoying.

Now she's an old girl (185k miles!), and has had a few sensor issues of late, but this one is driving me nuts!

Does anyone have any ideas how I can stop it happening?
Would appreciate any suggestions.

Great forums by the way! :D