Jon.
1 Copper

Re: Error code M1004

Folks -- My Inspiron B120 notebook experienced the M1004 overheating problem too.  So I searched for & found the service manual for it, & followed the suggested steps therein to safely access the parts involved. The culprit was the "microprocessor thermal-cooling assembly". When removing it from the chassis, you could see that next to its outlet side (the downstream side re air flow through it), at the fan housing inlet point, the air inlet path to the fan was blocked with dust (like a self-supporting curtain, or like a dryer screen collecting lint -- but without the screen!). So this "dust curtain" was then manually removed, followed by reinstalling removed parts, & the PC now runs beautifully again!

It's amazing how sluggish the notebook had gotten over a period of several months, before I realized what the problem was (an alert finally appeared on the screen about overheating, after the PC began to shut down on its own). So now, it's its old self again -- the fast running notebook that I really enjoy.