Not Happy

I've been chasing my tail looking for a fault which was preventing Win XP. from fully booting. I have 2 drives from which I can start, neither would work. Fearing that this would mean a new motherboard, I've wasted a week. An hour ago I found the culprit. The new drive that I bought a couple of months ago has gone faulty, it would run but only boot sometimes and was upsetting the power supply. As long as it was plugged in the other drive wouldn't boot either.
Fortunately I haven't lost anything, after the last drive failure I've been backing up frequently.