Damien, just a heads up -- I had the same problem as you that went away just by looking at the fuse box and reseating everything, but a week later the problem came back. The real cause of my problem was a melted connector to the fuse box (just like SetiRich had in the link posted above by Tony2005).
If your symptoms come back I would recommend you look at the two-wire connector that plugs into the corner of the fuse box. I fixed mine by cutting off the damaged connector and crimping two 1/4" female spade lugs to the wires. The spade lugs fit nice and tight to the male terminals on the fuse box (which I cleaned with a wire brush to ensure a good connection). This avoids having to take apart the fuse box but, like SetiRich said, if the problem comes back at least you know where to look.