Unmountable boot volume errors are fairly common.
Some can be overcome by running the chkdsk /r command from the XP Recovery Console...some may indicate a problem with the hard drive itself or the partition structure.
Unmountable Boot Volume - http://support.microsoft.com/kb/555302
Looking at the graphic you posted...I'd say that you may have a weak/dying CMOS battery, based on the PXE error. That error normally indicates that the system is trying to boot from a network
and that is the default boot option on some systems, due to method of installing the O/S. When the CMOS battery weakens, it causes all sorts of strange errors in the CMOS...may provoke false messages about the hardware in the system, indicating problems where there really are none.
First thing I would do is boot into the BIOS...see what the first boot option is. If it's network, manually change it to your hard drive and save the change.
After the system reboots, let us know if you still get the error reflected in your graphic.
If the system still tries a network boot or you cannot change the first option...I would purchase/install a new CMOS battery.
"PXE-E61: Media test failed, check cable."