Headlight problem

I have a 97 LeSabre Custom, 3.8 V6.
When the headlights are on low beam, the passenger side low beam lights up OK, but the remaining bulbs (passenger side high beam, driver's side high
and low beam) all light up very dimly. When I switch the lights to high beam the passenger side high beam bulb lights up just as it should, but now the passenger side low beam and both the low and high beam bulbs on the driver's side all light up very dimly.
This started happenning last weekend, but after the lights had been on for about a minute everything started to work as it should. Now I can't get the lights to work properly at all. Is some kind of solid state switch involved here?
Can anyone shed any light on this problem (excuse the pun - I couldn't resit it).
Cal.
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now
the
involved
resit
Bad ground.
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Check the ground for the left headlamp.
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Thanks to both of you. That seemed to be the general consensus at work too, so I'll check it out.
Cal.

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