To save space on your computer's hard drive, PowerPoint now allows you to link pictures to a file on a CD-ROM or other drive (including pictures you have scanned and saved on your hard drive). When pictures are linked, PowerPoint loads the picture from the CD-ROM every time it uses the picture. If the pictures are not linked, PowerPoint makes a copy of the picture, stores it in the presentation, and saves it to your hard disk when you save the project.

Using linking has the advantage of not requiring much space on your hard drive, since it isn't making copies of the pictures. But it has a disadvantage too. The CD-ROM must be present when you show your presentation, otherwise PowerPoint won't be able to find the pictures that it inserted from there. When this happens, PowerPoint gives you an error message and puts a special symbol in place of the actual picture.

When this happens, PowerPoint gives you an error message and puts a special symbol in place of the actual picture.

As you may know, Windows drive letters start with a letter followed by a colon such as "C:" for the hard drive, "D:" which is usually the CD-ROM, "E:", "F:", etc.

When you use file linking, part of the information that PowerPoint uses to establish the link to the picture is the Drive letter. So if you put the CD-ROM in the "D:" drive, and insert a picture in to PowerPoint using the link to file option, PowerPoint will always expect that picture to be on the "D:" drive. On some computers, however, the CD-ROM drive is "E:" or some other letter. On those computers, even if you have the CD-ROM disk in the CD-ROM drive, PowerPoint won't be able to find the picture, because it will try to look on a drive with the drive letter "D:".

Use the Change Drive Letter macro, to tell PowerPoint the new drive letter. Be sure to save the presentation after you run the macro.