Sometimes with RAID, or SATA ports a drive might not be detected during a boot. When that happens Win XP rearranges drive letters to fill in the empty spot.
Watch the boot screen carefully at each boot to see if this is happening.
What mobo and chipset???
Toni Hackler has reported this happening to her computer frquently on a cold boot.
It might be a timeout problem where the drive is not found in the time allotted. The RAID and SATA part of the boot doesn't know if there should be drives there, so after a timeout if none is detected it simply reports no drive detected and continues booting. Doesn't require "hit F1 to continue", as with the boot drive if IDE.
Every now and then, when I turn on computer, I find that drive letters have mysteriously changed...anyone ever hear of this happening, or what causes it? Have to go to disk management, and set things right, which is a nuisance; but, if drive letter changed is for my second harddrive, will not allow me to change same...have to use system restore, to return things to normal. Any suggestions? I am running Windows XP Pro with SP2...two harddrives plus an external harddrive, and a DVDROM plus a DVD Recorder.