'Filesystem check failed! Totally 6 cluster accounting matches'
It looks like you are at a crossroads here. The most reliable and permanent way to fix the problem that you are having is:
(1) Back up your current xp partition and delete the partition. Then, recreate a smaller partition for xp and reinstall xp and your data. You then use the rest of the hard drive for your Fedora Core 4 partition. This option is desirable if you can do it but might not be practical for you.
(2) Install a 2nd hard drive and put Fedora Core 4 on it.