My wonderful 1999 XK8 for some reason occasionally,after putting key in ignition is dead,so I unlock the trunk,tap battery terminals,which are tight,and hey presto,she alive.
Anyone know why this happens and how I can fix her from doing this?Thanks

 

take off the cables and clean, but barring that you may have a broken/loose connection between the battery plates inside the battery. You might just want to replace the battery and clean the terminals when you do

 

Welcome,thanks BRUTAL Afor his prompt reply . For next time please you better use proper forums this is because this forums is made for welcoming new members and interaction rather than talking about techinical problems

 

Welcome aboard Calibrit, hope it is just, that simple fix.