Posted 27 October 2010 - 01:35 PM
You haven't told us how you accomplished this install...how many drives were attached to the system at that time...I will give generic info, which may help you to understand what happened and why.
First...if this system is an OEM (e.g., HP, Lenovo, eMachines, etc.) system and used recovery/restore disks or partitions...the manufacturer of those systems determines what your options are.
Second...if you have an actual MS Genuine XP CD and the system is self/custom-built...and you have an OEM CD...you need to be aware that Windows does a detection/count of all attached drives when it does the install. For every drive other than the optical drive used...and the hard drive to be used...the install routine assigns a letter.
C: is the first letter assigned, then D:, and so on.
If the install routine detects one hard drive and one optical drive...it assigns C: to the hard drive, with D: being assigned the optical drive.
If the install routine detects any other drives...either the install won't complete or it will assign letters to those drives. This includes flash drives, USB-connected external hard drives, and external devices which have been added to the system (such as card readers).
When ready to actually do the install...the routine goes through any letters it has already assigned to detected devices on the system...and then it assigns the next letter to the actual install.
Once this occurs and the boot drive has a drive letter other than C:, the only way that I have found to correct this...is to temporarily disconnect the devices which interfered with the original install...and then do a repair install of XP, with just one hard drive and one optical drive connected/detected.