Xp restarts during boot

After slowing down and, freezing occasionally, windows xp now continuosly restarts during boot up at the “loading windows xp” screen. Now when it restarts I get a screen that says “windows did not start last time…” and boot up options. I get the same result in trying in safe mode. Thought it might be power supply, replaced it. Same result. Swapped hard drives. New one boots up..but windows doesn’t see my cddrive. Bios confirms the cddrive is installed but windows doesn’t see it. My main concern would be the initial hard drive that is restarting on boot. It would be nice not to have to reformat. Alot of info gone. I would beg for any help I could get. Thanks, Ridge