A quick dab of the soldering iron fixed the problem but then I spent a couple of hours correcting data. Had a good look around inside the console but didn't find any more suspect joints.
The problem was probably aggravated by me having to remove the USB cable to allow me to start up any games that use DirectX9. (shut down Cumulus 1st)
I will update soon to Windows 7 just to avoid the DirectX problems.