Ha! Weird problem, undid the machine to take a look at the innards, and noticed a slight rattling sound. Odd, but get distracted and take a look a the hard drive. This has a yellow sticker on it bearing the legend Drive 1, and someone has written in marker across it Windows 7. Interesting.
Think about this for a while. This is after all a new custom built machine. Then move the machine around to see where the rattle might be coming from. It seems to come from the fan, which is a stock Intel fan and heat sink. Odder and odder.
Waggle it a bit, and it comes up easily on one side! In short, three of the four securing pins are not secured into the main board, so presumably the fit of the heat sink is, well, dodgy.
Oh dear. This might be the solution. In the meantime my friend lost his sense of humour and trashed all the previous partitions, well, hard to blame him. So here we go again....
Peter