Starting problem

Hi folks,

My Citi has developed a strange problem when I try and fire her up.
On Friday I was due to leave work, and got into the car to start her - all clocks/dash lamps etc. where fine. As I turned the key in the ignition, all the lights and LED clock etc. vanished, and she had no power at all. She wouldn't turn over, it was as if the battery was totally flat.
I have a relay mounted in engine bay for the full beam lamps, and it has what appears to be an earth wire under it, bolted to the wing. When I fiddled with this the power came back on and the car started.
I'm not sure what this earth is for, or why it interferes with the starting of the car, but she did it again this morning, though very quickly and fired up at the second key turn.
Has anyone else experienced this?
96' Citi Golf 1300.

Thanks!

sounds like it might be the main battery earth to the chassius? follow the wire anmd see where it goes

Unbolt the earth from the chassis and give the wire and the mounting point on the chassis a good clean with some fine sandpaper.

Thanks guys,

You where spot on!
The earth from batt neg to chassis was rusty and gunked up - took it all off, wire brushed and bolted back together and all is well.

Is there anything I can put on the earth to prevent future corrosion?
Someone mentioned vaseline!?

aye vaseline or grease will work fine.