ERROR MESSAGE ON START UP

WHEN I BOOT UP MY P-4, I GET A ERROR MESSAGE THAT READS MISSING——EMM386 NOT ABLE TO LOAD PAGE–I HAVE CHECK AND RECHECKED DIFFER MANUALS AND I CAN NOT FIND WHAT THIS IS OR WHAT TO DO. THIS A CUSTOM BUILD PC MY MYSELF,IT`S MY FOURTH SYSTEM I HAVE BUILD AND THIS THE FIRST TIME I HAVE HAD THIS HAPPEN.I AM RUNNING GeFORCE VIDEO CARD WITH A 100GIG HD,512 RAM AND A 5.1 SOUND SYSTEM WITH WIN98SE FOR A O/S.MY HD ARE BOTH MAXTOR A 60GIG AND A 40GIG AS A SLAVE,I ALSO HAVE A SCANNER AND A PRINTER ON THE SYS.