Probably corruption of XP on an old hdd that has bad sector after so many years.    To revive this old pc try find old XP installation cd and do a clean install.  If still not good, hdd needs to be replaced.
I have a dimension 4700 and when i try starting it it goes normally untill i get to the windows xp start screen and thwn it goes to a blue screen and at the bottom has a bunch of numbers and zeros ill type what it says  UNMOUNTABLE_BOOT_VOLUME ***SROP: 0x000000ED  (0x82384900, 0xC0000006, 0x00000000, 0x00000000) It also foced me ro pick a location and i didnt know wich one to pick
Dimension 4700 goes to stop blue screen