Hi,
I think you should first setup the correct version of gcc (4.3) For example, with bash (64bit):. /afs/cern.ch/sw/lcg/external/gcc/4.3.2/x86_64-slc5/setup.shAnd with [t]csh (64bit):
source /afs/cern.ch/sw/lcg/external/gcc/4.3.2/x86_64-slc5/setup.csh
For 32bit, simply replace x86_64-slc5 by i686-slc5.
Cheers, Bertrand.