When you install or update a CS4 or CS5 product, Acrobat, or Adobe Reader on Windows, you receive the following error:
Choose Start > All Programs > Accessories, right-click Command Prompt, and choose Run as Administrator.
Type subst Z: "C:\Windows" and press Enter.
Note: The example above shows the letter Z as the drive letter. When you type, replace the Z with the letter of the invalid drive from your install error or log.