My HP dx2250 desktop suddenly refused to turn on last Tuesday; it just beeped loudly at me when the power button was pressed. It took me until today to look at it; downloading the troubleshooting guide, I could translate the pattern of flashes of the LEDs as signalling faulty RAM. Phew.
I must say I was surprised - I have never had RAM die on me before. At least it wasn't a DIMM module I had bought myself... and it could be worse, I was almost considering replacing the machine. (I wonder how many people do.) For now, I'm down to 1GB RAM, unless I can find something stashed away somewhere.