TS4: security block is missing ...?

[Simon Campbell <simtrader@xxxxxxxxxx>]

I have a relative who used TS4 a few years ago (he still has the old build 
18 non y2k CD).  Since he wanted to install TS4 from scratch on a new PC, I 
sent him a spare build 23 CD of mine.  So he loaded it up and got a 
"security block is missing" message, despite it being firmly attached!

I'm wondering ...does anyone know ...
Did omega code the CDs so that they have a particular person's security 
information on it?  I can't imagine that's the case.  But he is trying to 
load a CD originally sent to myself ...with HIS security block.

This is a fresh installation on a new PC.  He's using Window's ME as his 
operating system: my guess is that this is the more likely culprit?

Suggestions welcome.

Thx
Simon.