E1405/640m beeps on startup.

Hello,

my name is Emily, and I am upset my well-loved (but geriatric) laptop has started to beep at me on start up.

It's always given me two short, mini-beeps when I first turn it on. They're fairly muted beeps, and they've always happened. Recently though, it's been giving me an ANGRY beep when it gets to the user account page/user selection for XP. It's like the difference between someone tapping you twice on the shoulder and someone whacking you. But that's all that happens. There's no warning messages or text that appears, it's just the angry beep, and then it proceeds to run as usual. 

Today I opened up my machine to clean it and pulled out copious amounts of hair (mostly from the keyboard, but some managed to get into strange places), dust, and who knows what else. I was hoping this may have fixed the problem (the microprocessor cooling assembly looked more like a dryer lint screen when I pulled it out), but alas, my machine still gave me an angry beep on start up. I'm glad I caught how nasty the microprocessor cooling assembly had gotten, but I'd still like to know what's going on.

I've done some googling on this problem, and from what I understand the beep is some sort of way of my machine telling me something's wrong and I need to fix it. However, I have no idea what this single, loud beep means. Does anyone here have beep codes for the Inspiron e1405/640m, or any ideas or insight as to how I can fix it?