Have a Gateway GM5474 w/

Question

have a Gateway GM5474 w/ Windows Vista SP1 newly reinstalled. it was reinstalled b/c it kept randomly freezing up and no problems could be found or sloved by Windows Pc repair or other. Now it still continues to randomly freez, and has missing drivers for the Visx Pure tv-u 4899 (NTSC/ATSC combo)and other multimedia device. What can I do????