The cause seems fairly obvious. It remembers the last track that's clicked on and processes that one first. If highlighting a nuber of files in order (like a CD), the first click picks the first track, the shift key is pressed, you click on "add" and the stupid thing picks the last one in emory - the last track, adds that and then adds the rest.
One would think it would be an easy thing to fix. Especially as it doesn't seem to happen using anything else bar Nero Express. They obviously feel it's not worth the investment considering most people would probably have used the Multimediasuite10 and Express is an older program.
I only noticed it this week after finding my old favourite Express hidden within the burning rom options.
One of those things, you like to use what you always have (plus there are a few more options in express).
It never happened with Nero 6 by the way (I used that for a heck of a long time but it won't work with 64bit systems so I had to buy a new version - and it cost a LOT).

Thanks for all the help. I just need to re-burn some CDs now although, with a loop, I don't suppose it matters really.
Not my day today. I already posted a reply earlier and it seems to have vanished into the ether!