So, I have an older Mac Pro 2,1 that I received. Had a fresh install of Mavericks and nothing else. It worked fine, with exception to slow redraw speeds on the screen. When I got it plugged into a network for the first time, it said there were updates, so I let it do the updates.
When I returned to the machine, it was simply sitting at a white screen. After waiting several hours with no change, I turned the machine off, and rebooted. I was met with the flashing question mark on a folder icon.
The Mac has the Apple RAID card in it, and 4 1TB drives.
Pressing any of the startup commands during boot does nothing; I still get the flashing icon. CommandR doesn't work. C doesn't work. The only two that do anything is CommandOptionPR (reset NVRAM) and Option (Startup Disc select). However, even when using those two, they still result in a flashing question mark icon.
Any clues? I'm wondering if the RAID card went bad or something. It was complaining of a bad battery.