Whenever I turn on my computer, I see a flashing folder icon, occasionally interspaced with a globe icon. I read elsewhere that this lasts for several minutes, but it can go on for an hour without pause. I tried booting up from my install disc, but couldn't get the computer to acknowledge it. I was able to start installing with a 10.5 upgrade disc, but was unable to complete it because the computer did not already have 10.4 or later on the HD (for the record, I was on 10.5.8 before it crashed). I tried restarting it from the Network, but that didn't seem to help either. I can't even access my HD through a firewire cable; the HD simply won't show up on the host computer's screen. I'm pretty sure this means that my HD is hosed, but I thought I'd ask to make sure. Anything that I might be able to do to fix this?