Just an update to say that I updated the BIOS on the mobo and after that, rebooted and immediately went into the BIOS ... and I could see that it now saw the whole 250GB ... and then let it reboot ... and XP came up and everything seems to be there and OK ... well, CorelDraw 12 would not really run, so I uninstalled it and re-installed it and it seems to be OK now. There may be other things that were lost during the Ccleaner action that I will discover.
But has anyone heard of anyone else having a similar problem ... where the BIOS didn't really recognize the drive over 137GB, but WinXP SP2 did ... and an install took place ... and Ccleaner somehow clobbered the system?