On Sunday my desktop computer was not well. A bit of investigation suggests it has a dead power-supply. It's 7 years old and the DVD-ROM died about a year ago, so it's not surprising that bits are starting to die - soon it will be time to replace it.
Today we got home and a friend had dropped a spare power supply unit off to test and at the moment all is working well - so I know the motherboard isn't fried and it's worth ordering a new "silent" power supply for £30ish to keep the PC running for another 12-18 months until I'm ready to upgrade.
On Monday I blipped the inside on my PC today it's the grill on the dead PSU.