Windows 7: Stuttering sound and performance drop during startup and file transfer

I am experiencing this on my Asus U46SV laptop with Seagate Momentus XT 500 gb onboard. Recently, whenever I startup the pc, I get the windows startup sound which is stuttering. I have no idea why. I do see the programs are still being loaded when the sound is being played.

Sound stuttering also occurs when I play youtube videos. Not only does the sound stutter, but the video stutters as well. Tried a video file on the pc, same thing as well. Stutter sound and significantly stuttering video or if not slow video playback during file transfer.

Is there something wrong with the HD or will a simple clean install solve this problem? I've never had this problem on any of my 5400 RPM laptop HD or 7200 RPM desktop HD before.