"autochk cannot be found" goes into startup loop. recovery control

comp wont start--goes into startup loop after "autochk cannot be
found--skipping autocheck" started up recovery console as far as command
prompts--but not sure what to do from here?!!? tried "fixmbr" and
said---caution---this computer appears to have a non-standard or invalid
masterboot record; but then has an ominous warning about losing
files/partions,etc---scared me off. any ideas??? thanks in advance!