What is the output of

rpm -q gcc 4.1.0-25

rpm -q cpp 4.1.0-25

If you have them installed, as you say, then I suspect they are of different versions. they need to match

Also do

rpm -V gcc rpm -V cpp

both display nothing, don't know if it's normal

just to make sure they aren't corrupt. If they are, you'll have to reinstall them

After you have a working gcc and cpp, you need to do

cd /usr/src/linux make mrproper make cloneconfig make scripts make prepare-all