glibc 2.3.6 issue with ld.so and shared libs

[john h]

I'm getting the following error when testing an app that uses libc and
libm shared libs.  It finds the so file, but isn't happy with it.  We
have recently moved from 2.3.3 to 2.3.6 and moved to using crosstool
to build our tools as our previous build process was not good.

/ # ./hello
./hello: /lib/libm.so.6: version `GLIBC_2.1.3' not found (required by
/lib/libmso.6)

I can use the ld.so from the same version of glibc and the
non-crosstool build and it works fine such that we believe ld.so is
the issue.

We don't really understand the versioning and symbols in glibc well,
is there anything that explains it?

Any pointers would be appreciated.

Thanks,
John