Strange sounds after boot-up

I'm running Vista Home Premium on a 5 year old HP Media center.

Other than this problem, the computer seems to be running good.

 

I'm using the latest version of Norton Internet Security.

However, I recently got an awful looking horizontal lined green screen with falling white  snowy speckles after a boot-up and was completely froze-up.

I had to hold in the power button to shut down.

 

I then rebooted using “Last known good configuration” and everything then worked fine for a couple of days.

Then, after a couple of days, a Norton alert came up saying that it could not initialize the ‘intrusion’ segment of the program. 

From there, it said that I needed to reinstall the program.

 

I went to the Norton site and followed the instructions on that procedure

and everything went good.

I then ran all of the updates and then ran a full system scan, and everything came up clean.

 

But – now I’m getting a strange sound when I boot-up.

It sounds a little like a weird kind of hollow drumbeat.

 

Everything seems to ‘drag’ when I first boot-up, then after about a minute the sound occurs.

Then it occurs again about a minute later, and then a third time about a minute after that.

After the third occurrence everything seems to be ‘freed-up’ and works normally.

 

I’ve recorded it and I hope that you can listen to it from the following link;

(Right Click, Save As . . . or maybe copy, paste into a new browser)

[removed broken link]

 

Even though my Norton says I’m not infected, I’m guessing that this might be a virus or something. 

So, even though I prefer not to, I’m thinking of completely ‘re-formatting’ my hard drive.

 

Or if not, could it be a sound card or other kind of ‘hardware' problem?

Can someone help?

 

With appreciation,

Charles

 

[edit: removed broken link]