BUG -- Apps made on FC5 (GCC 4.1.1) do NOT run on FC3 (GCC 4.0.2)

[Ignoramus20785]

We have an app that we compile on FC5 (Fedora Core 5) using g++ from
GCC 4.1.1.

When we copy our app to a FC3 server, to run it, we get this error: 

our_program: /lib/libgcc_s.so.1: version `GCC_4.2.0' not found (required by 
our_program)

Further investigation was done with command

$ objdump -T our_program|grep GCC_4
00000000      DF *UND*  00000019  GCC_4.2.0   _Unwind_GetIPInfo
 
That means that of this big program, only one function
_Unwind_GetIPInfo requires symbol GCC_4.2.0 to be defined. All others
need GCC_3.*.

That symbol is mentioned in /usr/lib/libstdc++.so.6 and /lib/libgcc_s.so.1. 
My guess (which may be wrong)  is that libgcc_s defines it and libstdc++ 
requires it. 

My main question is WTF?? Why would only one symbol require a new library?

What can I do to get C++ apps compiled on FC5 to run on FC3?

I am very desperate for help. Thanks a lot. 

i