If you receive: Please insert Disk #2, repeatedly, during your SBS 4.5 VUP, from SBS 4.0x, even though CD-ROM 2 is mounted, I have an 8 step workaround:
1. Carefully place CD-ROM 2, silk-screened label up, on a non-abrasive surface.
2. Remove the cap of a Magic Marker, or similar permanent marker.
3. Carefully write a 3 on the silk-screened label.
4. Place CD-ROM 3 on a non-abrasive surface, silk-screened label up.
5. Using the instrument from step 2, write a 2 on the silk-screened label.
6. Replace the cap on the permanent marker.
7. Place the newly labeled CD-ROM 2 in the CD-ROM drive.
8. Continue the upgrade.