Sounds like a master boot record problem,
Full article -
http://www.ntfs.com/mbr-damaged.htm
The simplest way to repair or re-create MBR is to run Microsoft's standard utility called FDISK with a parameter /MBR, like
A:\> FDISK.EXE /MBR
FDISK is a standard utility included in MS-DOS, Windows 95, 98, ME.
If you have Windows NT / 2000 / XP, you can boot from startup floppy disks or CD-ROM, choose repair option during setup, and run Recovery Console. When you are logged on, you can run FIXMBR command to fix MBR.
Also you can use third party MBR recovery software or if you've created MBR backup, restore it from there (Active@ Partition Recovery has such capabilities).