configure: error: C preprocessor "/lib/cpp" fails sanity check - SOLUTION

I hit the following whilst try to compile apache on RHEL4 as part of Mapguide 2.0

checking how to run the C preprocessor... /lib/cpp
configure: error: C preprocessor "/lib/cpp" fails sanity check
See `config.log' for more details.
configure failed for srclib/apr
Apache build failed (0).

in plain english, maybe your kernel sources was missing (or skipped),
run up2date --configure to check for skipped packages, look for the item pkgSkipList

update -u "@KDE Software Development" was the tip to pretty much get everything you need

but it stil didn't work, so i installed apt, which then recommended apt-get --fix-broken install which cleaned up some stuff.

I then hit an error about not finding a shared gcc info file... then i simply re-installed gcc and bang it worked