I had a hard drive problem recently. I reloaded windows on a new drive, DLed a fresh install of AH2, DLed a new hirez pak and installed it. The only things I saved from my old drive were they custom sounds, and the head positions. After I got everything loaded, and set-up, I then defragged the drive.
Now, on the old HD (same speed drives, but new one is bigger) running everything full up I was getting 45-50 FPS anywhere, furballs, heavily damged bases, CVs on fire. Only place that gave me any trouble was tank town on island map.
Now on new drive I'm getting the same thing as Platano. Screen freezes for seconds at a time. Seems to happen when I'm in a fight with more than a couple planes near-by, or when Im scanning the views a lot.