In reply to mikeg.
Yes I have 12 copies on 12 computers but from 3 disks (sorry I should have clarified the number of disks).
1 disk has my own (teacher computer) copy. 2nd disk has 5 copies for the first 5 computers bought in 2000.
The 3rd disk has 6 copies for the second lot of computers in the second music suite room in 2001. I have found that the copy from one disk will not de-install onto one of the others. Registration number won't match. Thanks for the point from
sascott, I have not thought of the disk possibly ever becoming corrupt. However, one copy of the second installations in 2001 did become corrupt when installing Sibelius. With the disk sent back to UK with a letter from the RISC OS agent (who installed it) we found that Sibelius copy could be replaced without any problems.