dudes help me out

i'v been havin this prob for quite some time and its reallllly buggin me

each time i start downloadin somethin either my comp suddenly restarts or limewire mysteriously shutsdown
&
when i re-open limewire it seems to have forgotten my downloads
i tried to restart the downloads by resuming them from the incomplete files but it only starts again from 0%

wat do i do????????