Here is a scenario that shows applying this approach to an actual problem. A user was trying to upgrade a home computer to a newer version of Windows NT 4.0 (before the final product was available). The user was about half finished with copying files from the CD to the hard disk when a message appeared saying that a file could not be copied. This was how the user isolated the cause of the problem.
The user has successfully installed earlier versions of the software on this computer. Since the last upgrade of Windows NT, the CD had been used to install another program, with no problems.
Nothing has been changed on the computer since the last upgrade, except installing the other program. That program should have no relationship to the problem. Other people can install the same version of Windows NT from CD on similar computers.
The user noticed that the CD-ROM drive made noises like it was spinning faster and then slower just before the error message.
These are the steps that he used to identify and recover from the problem.
Step 1. Check the event log to see if there are any errors logged. The CD ROM device was reporting bad blocks on the CD, so Windows NT knew that there were problems.
Step 2. Inspect the CD for dust or scratches. There were no obvious problems on the CD, and the user previously had no problems using the CD.
Step 3. Copy files from the CD manually rather than running Windows NT Setup. The file that caused the error copied fine, but other files on the CD could not be copied.
Step 4. Get another CD of the same version and try to install Windows NT from it. (Perhaps there is a problem with the CD itself.) Windows NT Setup failed on the same file on both CDs, and manually copying files fails on the same files.
Step 5. Install software from other CDs that have worked on this computer before. The user noted that some work, some do not. The ones that do not work have more data on them than ones that install successfully. Therefore, something must be wrong with accessing data on the later tracks of the CD. Data is recorded on CDs starting on the innermost track. CDs vary their spin rate when reading inner versus outer tracks. Something might be wrong with the motor synchronization spin rate.
Step 6. Look inside the CD-ROM drive for signs of dust or hair that might interfere with proper operation at one end of the read head's range of motion. A hair was found stuck to the read head.