Hi Jazzman,

Thank you for your quick response. I am updated to 2009.5 plus realtracks updates.
It was a good point that you made about a disc-clean and defrag - that's something
which I am a bit tardy about and have now done both at your prompting. Will try
to do it regularly in future. If it hasn't cured what I was enquiring about at least it's
good for my PC.
I think mac has hit the nail on the head re my query - I am replying separately to him.

Thanks again,

Ken