When I open XL I get the error 1004, indicating that it has a problem loading
funcres.xla and the rest of the startup .xla files.
It seems that there is a problem with the VBA module, since the Visual basic
editor is not available and of course no macros or any other custom code can
run.

Although there seems to be a problem with the entire office system
installation (every time I start word it runs repair before it goes on, for
example) Visual basic editor has been installed and is available in other
parts of Office, like Word or Access.

I tried to re-apply SP2, but nothing. Then I reinstalled office and applies
SP2 but still nothing.

What could be the problem?