Xsara Picasso is auto locking but central locking on delay

[yorkshiremanjjim]

Hi all,

For some reason my picasso (55 plate) has started being weird. If I lock the drivers door with the key it only locks that door, but about a minute later, you can hear all the doors auto lock.
If I do it by the passenger side, it does it immediately as normal.
I can't work out why it's doing it. I thought it might be an issue with the door wires as the window on that side is hit and miss as to if it will move, but it's really odd that it will always lock all the doors like a minute later.
It's not like it's broken the connection as it does it with a delay, and that it will also lock when you do it via the passenger side.

Any thoughts on what I can do?
It seems to always lock, but i'm paranoid it wont, so always have to go round the other side to lock.

[PaulC5]

Maybe the switch within the lock has dirty contacts so takes a while to work. If you use the key in the lock several times in quick succession does it make a difference ?