This sounds like it's happening in your initial installation of Office 2003.
If so, it's usually a problem with either the CD or with your CDROM drive.
First, I would check to see if the CD is dirty. If it looks dusty, wiping
with a soft clean cloth will sometimes help. A dirty CDROM drive can also
cause a problem reading the CD. Blowing into the opening of the drive can
sometimes help. After doing this, try to install again. If that fails, try
copying the CD to a folder on your hard drive, and try installing from
there.
If these steps fail, contact Microsoft Product Support to request a
replacement CD.
Sloan Crayton
Microsoft