Peugeot 206 Lights Problem!?

[lsharp]

hiya i noticed today after parking up, turning engine off and locking car that the front side lights and rear lights were flashing....odd as never happened before so i put my immobiliser is and it stopped, went indoors came back out done the same when i put ignition on....hasn't done the same since!!
any idea what it could be? it's going into my garage tuesday for a belt replacement so i will get them to look then but just wanted a rough idea if anyone knows?
thanks

[TWR]

The Alarm is activated Isharp, our 206 does the same, when it does'nt do it you have a security problem.