RHEL3: Problem going from RH 2.4.20 to Linus 2.4.33

[David Douthitt <ssrat mailbag com>]

I compiled a version of Linus' kernel 2.4.33 for CentOS 3 (RHEL 3) and 
found that several programs started failing with core dumps or lockups.

It seems to center on two different things: the clone() call, and some 
kind of file locking call that isn't supported ("fuserlock"?)

The clone() call resulted in core dumps; the other resulted in 
programs receiving an unexpected "not implemented" result and entering 
an endless loop waiting for a positive result.

Any tips?  I'd like to keep the kernel current....