As the title says, PC boots to a blinking underscore. No BIOS screen. No USB detection, so can't access BIOS. I've changed CMOS battery, removed HDD. No change.
Its a Dell XPS 400 that originally ran XP. Has been upgraded to 32 bit Windows 7 and has run fine for over a year since the upgrade.
The initial issue was a frozen boot. The user left it running over the weekend (in-house PC, user has always left PC on 24/7) and it was at the Startup Repair/Normal option screen this morning. I rebooted and it went to the blinking dash, rebooted again and it showed the BIOS prompt, but froze before all the text appeared. Rebooted again and ever since has gone straight to the blinking dash.
The HDD seems to be ok, I don't have a proper testing PC at the moment.
Would this be a motherboard issue? RAM? If so, what would cause it?