couldn't hurt to call up your cable company, and request a new modem that will actually stay on 24/7 without a problem, thus giving you what the Cable internet service is - Always on.
though, I use an old Cable modem, as the newer ones did overheat, and shut off. after a few service calls, including one in which the newly brought modem shut off as he was preparing to leave ("you're not leaving yet"), we got an old style modem, which has worked flawlessly. heck, I've had to reset my router more often.
Road Runner, and use an old Toshiba 1100U cable modem