Hi Paul,
I believe this is an occurrence of a problem that has already been reported in our quality control center (
http://quality.runrev.com/qacenter/show_bug.cgi?id=6975).
The bug proved to be rather hard to reproduce on our test systems and I believe that it may depend on something you have set in your Revolution preferences.
Probably the best way to test this is to reset your preferences and see if the problem goes away. However, before you do this, if you make a backup of the old preferences stack, this means that you can restore your prefs if the problem doesn't disappear, and it also means that you can send us the broken prefs file for testing.
To locate your preferences file, open up Revolution, and using the message box do:
put revEnvironmentUserPreferencesPath()
If you then browse to this folder in the Windows explorer, you need to make a backup of the file "revPreferences.rev".
To reset the preferences, either go into Edit -> Preferences and click the "Reset Preferences to defaults" button, or simply delete revPreferences.rev and restart Revolution.
The easiest way to send the broken prefs file is probably as an email attachment to support at runrev dot com, quoting the path of this forum thread so that whoever picks up the email knows the context.
Hope this is some help.
Regards
Oliver