Since the power cord is actually a step down transformer, that is taking 120 volts input and 18-19 volts output. the problem usually is input voltage. Too much or too little voltage can damage a transformer. Since I have never came across this, i am trying to troubleshoot the cause. Voltage spikes will fry it also. Never have come across a bios causing anything like this. Do you use the cord only at home or do you use it in different locations. A surge protector might be a solution. I would ask if you use long extension cord 16 guage or smaller, but normally the total wattage of these laptops are not that much. (long extension cords have voltage drop). I would check voltage at outlet where computer is plugged in to see if it fluctuates.
I may be barking up the wrong tree, but let us know if you figure it out.
XPS (product red) M1530, A12 bios, Intel C2D T9300, 8 Gb (2x4) G-Skill Ram, 1 Gb Intel TCM, WD 320 7200 rpm hd, Intel 4945 wireless card, Sprint broadband card, bluetooth, x-fi express card, Hp Digital express card tuner, Vista Ultimate x64 sp2
ashame you couldn't have found a way to record that wonderful advice ... it would have made a great youtube video.
that said, if the computer is still under warranty, it is probably worth upgrading to the latest bios available.
Latitude D430Dimension 9150Dell 1815dn Printer