1. Try burning at a slower speed.
2. Replace a broken CD burner.
3. Shut down all open applications.
There are actually a few different things that can cause buffer underrun errors. It is generally helpful to make sure that the computer has as many available resources as possible. Sometimes this type of error can be prevented all together, by burning the CD-ROM at a slower speed. If the CD burner is no longer functioning in the way that it should, replacing it may be the only way to prevent such an error from occurring.