Reinstall the application that causes the message to appear.
Thanks a lot! It's a simple answer but it worked straight away.
Just a caution though! This was in connection with Adobe reader 9, which I deleted. I reinstalled Reader 8, and this is much "leaner" than 9 and does all I want.
Now, how do I stop Adobe constantly bombarding me with requests to update? I don't want to hear from them until I contact them without their incessant pressure.
All the best,