Problems may occur even if you have installed Windows 7 on a separate partition on the same Hard Disk having Windows XP installation or if you have installed both on different hard disks. The Windows Boot Manager troubleshooting becomes slightly difficult in case of multiple hard disks.
Multiple Hard Disks: If you have installed both Windows XP and Windows 7 Release Candidate on separate hard disks, you can check if the BIOS is reflecting all the hard disks on your computer. While booting your computer, press the key that takes you to the BIOS. Normally, it is either the DEL key or the ESC key. It differs from system to system. The key to be pressed for BIOS access is displayed on your monitor as your computer prepares itself to load the operating system.
Once you access the BIOS, check to see if the BIOS is showing all the hard disks on your computer. If any of them is missing, you may have to call the hardware engineer or technician. If you know how to use the SCSI cables and jumpers to set up primary and secondary hard disks, you can do it yourself. This should solve the problem. If you still face the problem, you will have to follow the steps given in the following paragraphs.
Single Hard Disk: In case all the operating systems are on different partitions of a single hard disk, you can use the Disk Manager to fix the problem. Right-click on the Computer con and Click Manage. You will get a window that has two panes. In the left pane, select Disk Management. Depending upon your computer’s speed, the Disk Management Service takes some time to display each disk attached to your computer, but the drive information will appear in the right pane. Please note that each row symbolizes a different storage device and shows the different partitions on that particular drive.
Once you locate the partition where you installed Windows XP, all you need to change the drive letter associated with the partition. Please do not make any changes to the partitions containing Windows 7 Release Candidate, as that will create further problems. Right-click on the partition where you installed Windows XP and select Change Drive Letter. In the dialog box that appears, click on change. This will give you a list of available drive letters. You can select any one of them.
However, it is recommended that you choose a minimum of two letters above the current one. For example, if the list shows the drive letters starting from H, you can select K as the drive letter for Windows XP. This is to avoid future problems as you may be using other plug and play devices that require a drive letter. Selecting a higher Drive letter helps avoid possible conflicts with those external devices. Once you are done with the Drive letter selection, click on OK to close the window. Click on Start, Turn Off, Restart, and you are good to go.