I had a look round the BIOS, nothing seemed to be amiss. Decide to power down and leave few a few minutes. Powered it up and immediately the power (?) light on the front of the PC flickers but nothing else happens. The monitor power light flashes gently indicative of no data signal so the graphics isn't getting going. I tried 3 or 4 times but couldn't get past that point. No idea why the power light flickers in that situation.
Looked around inside, moderate amount of dust but I've seen much worse, nothing appeared to be loose.
I'm picking it up in the next day or two to bring home to look further, check power connections, graphics card seating, etc.
Clearly the fact that it scrolled the list of drivers on the Safe Mode load means the HDD is not (completely) faulty. Though any of memory, mother board, PSU, could be problematic - the PSU is a 250W LiteOn (IIRC).
Any thoughts on what may be wrong?