So about 86 % of all BSOD are caused by faulty drivers. All you need to do is find the driver causing the problem and keep it from loading during the kernel boot phase.
There are a couple of ways of doing that. First by disabling the auto reboot, so you can write down the error message. If you can’t boot at all, enable boot logging.(Press F8 for accessing safe mode)A text tile are created (ntbtlog.txt at system root) containing information about the boot sequence. Then boot from recovery console, and copy the file to a floppy. ( use the following commands )
set allowallpaths = true
set allowremovablemedia = true
Another way is to boot in safe mode(only the small subset of your drivers will load ), and take a note of any log files.
You can also download the Administrator's Pak Emergency Version from winternals, boot from erd commander 2005, use its system restore feature and access any restore points created on your system.
http://www.winternals.com/Products/AdministratorsPak/EmergencyDownload/Default.aspx
Inaccessible boot device, That’s a new error right?
It seems that you have configured the boot.ini file wrong.
Boot from recovery console, and run bootcfg /rebuild