I've searched and searched on this. My friend's laptop had this problem....

"we apologize for the inconvience but windows didnt start sucsesfully" then you can pick between start normally and 3 differnet types of safe modes, now when you click any of them, the same blue screen shows up and it says

a problem has been detected and windows has been shut down to prevent damage to your computer.
UNMOUNTABLE_BOOT_VOLUME
If this is your first time you've seen this stop error screen, restart your computer. If this screen appears again, follow these steps:
Check to make sure any new hardware or software is properly installed. If this is a new installation, ask your hard ware or soft ware manufacturer for any windows update you might need.
If problem continue, disable or remove any newly installed hardware or software. Disable BIOS memory option such as caching or shadowing. If you need to use safe mode to remove or disable components, restart your computer, press f8 to select advanced startup options, and then select safe mode
Technical information ***STOP:0x000000ED (0x817d58c8, 0xc0000006, 0x00000000, 0x00000000)

Now, ive done some research on this UNMOUNTABLE_BOOT_VOLUME thing, and i found specific information here
http://msdn.microsoft.com/library/default....267603c.xml.asp

on the other bugs, it tells you how to fix them but this doesnt have any information, which is where we need help. if anyone has had this problem and/or knows how to fix it please tell us. this happened to one of her other computers but they couldnt fix it then, and the had to get rid of the computer. if it helps, the version of windows she has is Windows xp professional.
thnx