Central Locking gone wonky - tuning chip box?

[B19GRR]

Hi all,

Got home last night, locked car and noticed that the dash was still lit up and so was the rear number plate - freaking odd I thought. Unlock the car and the lights went out. Lock again and on they come again. Sooo off I go to fuse box land and eventually find that pulling fuse 7 the lights go out - but then the central locking doesn't work

Now it maybe totally coincidental but I installed a tuning box yesterday - it's a PSI box I got from these guys:
www.dieselchiptuning.com/catalog/product_info.php?cPath=26&products_id=111

Now I can't see how that will mess up the central locking but you never know.

Any ideas folks? When I get the chance I'll pull the box and see if things go back to normal but it's a real pain as I need to remove the intake manifold to get at the connectors.

Cheers,
Rob
Dec '96 325TDS Touring