Blue screen Error

What OS are you using? there are many causes of blue screen error. like you said unmountable_diskvolume which means the problem is your HDD. try to format it or replace a new one.

Look here for your answer. There are several causes of this issue.

This error is commonly seen when with drive caching and using a 40 pin cable instead of the 80 ping cables.

http://www.updatexp.com/stop-messages.html

Sounds like a bad disk. Does it show up in the POST screen?

This behavior can occur if either of the following conditions is true: ? Your computer uses an Ultra Direct Memory Access (UDMA) hard disk controller, and the following conditions are true: ? You use a standard 40-wire connector cable to connect the UDMA drive to the controller instead of the required 80-wire, 40-pin cable.
? The basic input/output system (BIOS) settings are configured to force the faster UDMA modes.

? The file system is damaged and cannot be mounted.

RESOLUTION

Damaged File System
If the second parameter (0xbbbbbbbb) of the Stop error is 0xC0000032, then the file system is damaged.

If this is the case, restart the computer to the Recovery Console, and then use the chkdsk /r command to repair the volume. After you repair the volume, check your hardware to isolate the cause of the file system damage.

To do this, use the following steps: 1. Start your computer with the Windows startup disks, or with the Windows CD-ROM if your computer can start from the CD-ROM drive.
2. When the Welcome to Setup screen appears, press R to select the repair option.
3. If you have a dual-boot or multiple-boot computer, select the Windows installation that you want to access from the Recovery Console.
4. Type the administrator password when you are prompted to do so.

NOTE: If no administrator password exists, press ENTER.
5. At the command prompt, on the drive where Windows is installed, type chkdsk /r, and then press ENTER.
6. At the command prompt, type exit, and then press ENTER to restart your computer.For additional information about how to use the Recovery Console in Windows XP, click the article number below to view the article in the Microsoft Knowledge Base:
314058 Description of the Windows XP Recovery Console
If this procedure does not work, repeat it and use the fixboot command in step 5 instead of the chkdsk /r com