Wow - I had no clue there were that many include directories. I guess you installed the entire development category, huh? These ones jump out to me:

/usr/lib/gcc-lib/i386-redhat-linux/2.96/include
/usr/src/linux-2.4.18-0.4/include
/usr/i386-glibc21-linux/include
/usr/i386-glibc21-linux/lib/gcc-lib/i386-redhat-linux/2.96/include

I notice the /lib/modules/... directories that I mentioned weren't listed by your search. Do the directories even exist?

Edit: I just took a closer look at my directory structure and noticed that those were symbolic links on my machine. Never mind.

OK, after reading a bit - here's a fix that might work for you. Be sure to make a backup copy of the file before you try this.

In the file /usr/src/linux-2.4/include/linux/autoconf.h search for the following code:
Code:
#if  defined(__module__bigmem) || defined(__module__smp)
#define CONFIG_SMP 1
#else
#undef  CONFIG_SMP
#endif
and change it to:
Code:
#undef  CONFIG_SMP