Can't boot to XP after trying Windows 7

[RKA]

I have a Medion 8080 PC and installed Windows 7 on a separate hard drive so as not to alter anything on my existing hard drive. Windows 7 works fine, but when I reconnect to my original hard drive running XP I can not boot the PC at all and can't even boot from an XP installation CD. My bios settings appear to be unchanged.

What do I need to restore to be able to boot into XP?

 

[Jonmor68]

Change the drive boot order in bios to make the XP drive boot first.

 

[anand1]

I do not think that Bios setting has been changed as the role of Bios is to initialize all the Hardware and give control to the Boot Drive which searches for MBR.. It seems that your Boot files of XP might have been corrupted.

 

[Ryan Ashbrook]

IIRC, the Windows XP disc has a utility that will restore the MBR. Then you can modify it via Start > Run > msconfig > boot.ini

If I were you, I would check the msconfig option in Windows 7, to see if you can add Windows XP to the list.

 

[Kougar]

Did you install Windows 7 while the Windows XP disk was connected to the system? If so then Windows 7 changed the MBR on your Windows XP disk. If not, then as Jonmor said verify the BIOS is set to give the XP drive boot priority, it may be giving the native W7 drive boot priority.