"unmountable boot volume" problem or something else

[mak]

Not always but very often my computer freezes at the windows logo when starting up. when i try to run in safe mode i get the unmountable boot volume error. then i also get the error when try to start window normally and i have to run setup to use chkdsk to fix it. But even though i can get back into windows, this won't stop happening. Doe anyone know what the specific problem is and how to fix it?