[rodlittle]

Thanks for the reply, The disk is grey with a red exclamation mark 376GB
available and the comment is
You cannot install Mac OSX on this volume. To enable installation on this volume repartition disk as GUID Partition table
OK I should own up to the fact that I did upgrade the disk to a 500GB disk from the measly 90 it had, by copying everything onto the new disk and then swapping them. But that automatically formatted the disk into a journalled version
Im not a mac person but my daughter is so I may have done something unacceptable to a mac
rod