rundll??

when my xp loads up, i get an error of "RUNDLL...error loading...the specified module could not be found". i have no idea what this means...it is very annoying seeing that every time i boot up. Is there a way i can restore the xp files in the registry without deleting my loaded programs?
if someone could email me with an answer to "taybc@netlimit.com", it would be very greatly appreciated...