XP Pro troubleshooting.

My Laptop running XP Pro has developed a problem, can anyone help ? It refuses to open most on screen boxes, for instance, Taskbar and start up menu box, most boxes from my control panel, internet pages etc. They all appear briefly then vanish off screen. I would like to repair/recover it rather than format, but when you put a cd in and the menu comes up it forces it off screen as well. A second point is, i have dos start up floppies and have tried to format, but cant get the command to let me format. All i can get is A:\. Any ideas what i need to type in to get to the format C: stage. I dont have the original XP Pro cd, although i have a different one complete with the code, but it wont boot from this even when i have set it to boot first from cd. My file system is ntfs. Any ideas please,either to revover my comp or format it. Thanks.