Laptop making weird squealing noise/monitor flickering

[bills217]

I have a Dell Inspiron 9400 laptop that I purchased in May 2007.

Lately, it has been making an odd squealing noise while running (very high pitched, sounds like when your ears are ringing), which is accompanied by the monitor occasionally flickering or going out altogether (comes back when I restart). The noise changes slightly depending on whether or not I am hooked up to AC power, and there is more flickering when not hooked up to AC. The noise is unbearable. Tried taking the battery out and re-inserting, also powering laptop down and shaking it around a little, no difference.

The only unusual circumstances involving this laptop is that it has occasionally been in my backpack in my car when the outside temps have been 40ish, which I didn't think was a problem but now I don't know.

Any thoughts/suggestions?