Try running the XP recovery console form the XP CDROM (if you have one), or
from the multi-floppy set, which you can download from Microsoft. The
recovery console feel a bit like like DOS, but is really a command line
version of XP, with very limited capabilities. But, it can fix some common
things that prevent booting, like corrupt/infectd master boot record, bad
boot.ini file, and my favorite, is CHKDSK, which can fix file system errors.
Here are some links about the recovery console:
http://www.kellys-korner-xp.com/win_xp_rec.htm
http://www.wown.com/j_helmig/wxprcons.htm
http://www.xxcopy.com/xxcopy33.htm
If the recovery console can see the disk, run a CHKDSK /R and let it work,
possibly for an hour or more. If the recovery console can not see the disk,
think about repairing the master boot record. For help within the recovery
console, type HELP. For help with any command, type the command followed by
a space then /?.
Another way to fix software problems that prevent booting is to run a
"repair" installation of XP. For this you need a real XP CDROM, not a
"restoration CD", such as is often provided by PC manufacturers. A repair
install will leave your data and most settings intact. In contrast, a fresh
install or the use of a "restoration CD" will erase all user data and
programs.
Of course, if the problem is harware-related (i.e., crashed disk), no
software fix will help. One way to be sure that the disk is OK, without
using XP, is to boot from a disk-maker's floppy/CD and run a NON-destructive
test of the disk. Avoids options like format, or worse, low-level format.
Look for a 30-90 second quick test. All major disk makers offer disgnostic
software as free downloads, but some of it only works on their brand of
disks, so check the disk brand first.
