My computer cannot detect audio device?

I ve tried installing the intel chipset driver & realtek audio driver. when i start my comp the sound is ok & then suddenly there is a disturbance in the sound or if it's a video then the video also starts showing blockage & then again when the video resumes to play there is no sound & a red cross near the sound icon on taskbar. sometimes computer cannot detect mouse or keyboard either. Sometimes restarting helps & sometimes it doesn't. PLEASE HELP.