I used Update90.exe but still no luck!
When I use GC-Prevue to check my gerber files each physical layer is interpreted as 3 data layers instead of the usual one.
Data layers 1 & 2 don't seem to have any visible data, layer 3 seems to define the whole layer.
Anyway GC-Prevue draws the board correctly.
I bit the bullet (counted holes/sizes from the drill file) to get Ver 2.1 out to the board manufacturer.
This problem has been around since Ver 1.0 and the boards have been produced OK so I can live with it.
Thanks for your help.