Upgrading to Windows 95 May Disable an NT Boot Sector

• Microsoft Windows 95

SYMPTOMS

When you install Windows 95 on a computer running Microsoft Windows NT, The Windows NT boot record (NTLDR) may be lost.

CAUSE

This problem can occur for either of the following reasons:

• You are using SCSI hard disks on Micro Channel Architecture (MCA) computers.
• You booted the computer with an MS-DOS disk before installing Windows 95, thereby bypassing the Windows NT boot loader.

RESOLUTION

You can use the Windows NT Repair Disk that was created when you installed Windows NT to re-create the Windows NT boot record.

MORE INFORMATION

On an MCA computer, the highest SCSI ID must be the boot drive; whereas, the boot drive of an ISA or EISA computer is SCSI ID 0. Because of this, all physical hard disks on an MCA computer are listed, but they are disabled (or not listed) on an ISA or EISA computer (unless it is an IDE hard disk).

When you install Windows 95, it installs the boot record on the bootable drive. If the physical hard disks are listed in CMOS (as with MCA computers), any remaining boot records are removed. Since the boot record on a SCSI hard disk of an ISA or EISA computer is handled by a device driver, they are not listed in the CMOS, and Windows 95 does not remove them.

For information about restoring dual-boot capabilities after installing Windows 95, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q136547  
   TITLE     : Restoring Windows NT Dual Boot After Installing Windows 95