[JosephWebber]

My apologies for the delay in replying. I use the local library internet service and only get a limited time on it each day.
To reply to the various points (for which many thanks).
I originally ran calibre-0.8.33.msi and it has worked fine.
Last week I ran calibre-0.8.47.msi, but when I started Calibre bottom left of the screen said version 0.8.33 (confirmed by Properties/Version). I uninstalled 0.8.33 and reran calibre-0.8.47.msi – same result.
Both versions have been downloaded from your site.
I use Windows XP.
PS Last night I uninstalled Calibre from its usual location in D:\Utilities\Readers\Calibre and reran calibre-0.8.47.msi. This time I let it install to wherever it wanted to (which turned out to be C:\Documents and Settings\All Users\Application Data\Adobe\CSS\jre). It worked, so I moved all the files to D:\Utilities\Readers\Calibre and it still worked.
Very odd.
Thanks for your help.