It won't be the bulbs then - not if you can flash your lights. And it's certainly an electrical fault but it might have a mechanical cause - electrical faults usually do.
You have four lamp fillaments not working from the headlight switch - might be the headlight switch itself - might even be a realy if there's one in the circuit to limit and control headlamp use.
People might say it's an earthing problem but I would doubt it very much - ever so much.
It's a "common" problem - as in common to four different circuits Left/Right - Main/Dipped - the feed to the headlamp switch is a common point...
Good luck...
Peccavi
October 2009
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