Suse,
Glad I was able to help!
> Is there's a particular relationship between Html Help Viewer
> and Temporary Internet files.
I haven't quite got to the bottom of why HTML Help files need to make
use of the Temporary Internet Files directory, but it does seem to be
the case that Windows tries to place a copy of some of the CHM source
files in this directory when you view a help topic. If the directory
is full then this appears not to happen, which gives rise to the
problem you encountered (and some others too, such as the inability to
view the source of a help topic or Web page).
In any event, the fact that CHM files use Internet Explorer as the
display engine is central to the issue. Problems with the browser are
also likely to manifest themselves in problems with the help viewer.
--
Pete (Microsoft Help MVP)