I was using my laptop the other night when up popped Software Update informing me that I could install an update (think it was EFI...???) so it told me to make sure my mac was plugged into a power supply (it was) and to allow it to reboot after it had installed. It downloaded the update, then rebooted the system, after that I saw a grey screen with a progress bar that filled right up to the top. After this, the system 'rebooted', but when the screen went black that was the last thing I saw. No startup chime, no grey apple symbol screen, no keyboard response. The only thing that happens is the fan starts low and then continues to get faster and faster until it's nearly taking off... I've tried all the usual PMU/SMC resets - I've done the one where you hold the power button for a while, and the one where you hold shift, alt and option - still nothing....getting worried now!! Any ideas? I called Apple, all the guy could suggest was I take it into the store, the only problem with that being this is the busiest time of year where I work and I'm not going to be able to get there for quite a while......also I don't want to lose my data and presumably if I take it into the apple store they'll format the hard drive, right?? What can I do if I can't even get it into target disk mode?