This computer starts (the HDD light shows disk activity, so the PC is starting normally), but the monitor displays “no signal”

The no signal message could mean many things, from the PC being switched off, to a faulty monitor, and almost anything else in-between.

Next step: swap digital and analogue cables (Monitor & PC has both cables and plugs): still nothing.

OK, before I open the PC & test a new video card, I try a different monitor (I take the power cord from original monitor): Now the PC boots & I can see XP starting on my spare monitor.

This means that its not the video card that’s a problem, so its looking like a faulty monitor

I plug original monitor back in, and now it works too!

So now I suspect that the monitor might have needed a power cycle.

I normally see this kind of problem with motherboards… This is the first time I’ve seen a monitor with scrambled electronics that need a proper power cycle!)