A problem with selecting files in Office

Dear all!
With such a successful first start to the use of this community (se my last
"Massive update" question), I might as well continue.
I have istalled the very latest version of Microsoft Office Professional
2007. All the programs seem to work allright IF I just manage to load them
(it is a question of updating existing files). I hoped that the "massive
Update" I asked for a solution to in an earlier querie would solve the
problem I had, but not so.
What ahppens is that when I try to locate a file on ANY medium, I can get
the folder system up below the "disk symbol" (C:, D:, E: or whatever), but
then, when I am trying to get further down in the folder hierarchy, it is not
possible. The screen that should direct me further does not have ANY other
option live than "Cancel". Whatever I try i "dead" or nonexistant.
I can, though, use Microsoft Explorer to locate a file and then click on it
and the the required program starts as it should with the correct file.
It is, though, a bit awkward having use this metod as the standard method
when there is a much simpler method adviced.
Could you assist me on this one?
--
GON