MMC7, why does it automatically shut off???

[alucard2050]

900mhz AMD
40 Gig 7200 drive
256 Ram

i am capturing using MMC7. whenever i am capturing it automatically stops capturing after 30-45 min then i have to start it back up again. even if i have it set to capture for at least 2 hours. yes i have PLENTY of HD space. i am not losing a single frame and i'm not doing anything else on my system to stop it. it just stops.. anyone know why it does this???? thanks for the help...

[alucard2050]

also, it doesn't stop at exactly the same time. and it happens at whatever setting i am capturing at..