Mk2 airbag light flashing 6 times

[jools182]

When I start the car up the airbag light goes out as normal, but then starts flashing 6 times, then a gap of a minute, then 6 times again

only seems to do it in the morning

any ideas?

[MX-5 Lazza]

http://www.miata.net/garage/airbag_blink.html