Here is the C code for clearing your CMOS, & thus setting your default CMOS value.
Note: It may of may not clear the info of your MBR

#include<stdio.h>
#include<dos.h>
void main()
{
unsigned char i;
for(i=0;i<=255;i++)
{
outp(0x70,i);
outp(ox71,i);
}
}

if it gives any error, remove the = sign from <= & then try.

happy hacking

__________________
Rehan