Glad I'm not going mad 😄
If the final slash is not included, QuickTime thinks that it should look for the setting in the file
C:\Documents and Settings\All Users\Application Data\QuickTimeQuicktime.qtr
when it should be looking for
C:\Documents and Settings\All Users\Application Data\QuickTime\Quicktime.qtr
As my user's systems are locked down, they naturally do not have permission to create a new file in the first directory path. (And Quicktime gets very upset!)
Although I think QuickTime should qualify the path, it doesn't
It is, unfortunately, a similar story with other software I'm repackaging and athough I know about the problem, it can take a fair bit of time checking all of the registry entries