When using A1 or Regvac  sometimes not all entries are removed.
probably they are in use etc. Some programs remove such entries on reboot.
Does A1 & regvac remove them on reboot? If not is it a good Idea to have an additional
program to remove them? Perhaps you could comment on this.

   You are talking about two different things when you mention A1Click and RegVac.  A1Click cleans files off the computer and RegVac cleans registry entries.

   When A1Click cannot remove an item, it is usually a folder and it cannot be removed because it is not empty (this especially happens in the Temporary Internet Files folder).  This is nothing to worry about.  When it becomes empty, it will be removed.  Before then, it does not have to be and should not be removed.
   Another possibility is that a file has a filename with foreign characters that your computer does not recognize (this can happen if you used to have a different language installed on your computer).  I don't know how you would remove these files.
   The only other type of file that cannot be removed is an open file.  As you alluded to, open files can be removed when Windows is restarted.  I would rather not go there because files are usually open for a reason and it is best not to mess with them.
   I have known antivirus programs to keep temporary files open and thus block them from being removed.  In this case, uninstalling the antivirus program or removing the files through the antivirus program is the way to go.

   As far as RegVac is concerned, there are two reasons why an entry cannot be removed.  One is that it really is removed, but another program reenters it.  The second reason is because Windows does not allow some entries to be removed (Vista is especially bad at blocking entries from being removed).  There is no way to remove entries that Windows will not allow to be removed.

Ray,
thanks for the clarification. The registry I can understand.
Re A1:
I seem to have 9-11 files of the following types.
Index.dat, ~DFA05.tmp, Passwd.log.

It is possible that these are new files currently in use and the older files are removed.

My guess would be that they are open and that they are open because they are being used.

Thanks again. We can close out this thread.