Laptop troubleshooting forum: acer aspire 5920 - no power

We have 2x acer aspire 5920's at home - ours and our sons. Both have the Intel Core 2 Duo processor T5750 and run Vista, the only differnce is ours is 180GB HDD and just over two years old, his is 250GB and 14 months old. Our one has just stopped; no external trauma, worked perfectly prior to bedtime, dead as a dodo by breakfast.

When ours is plugged into the wall the AC pack pulses slowly with a pale light and no power reaches the laptop. This happens with both the AC pack for our laptop and our sons, yet when either pack is attached to his laptop they work perfectly with a strong solid light and power to the machine.

Again, swapping batteries has no effect in our machine yet both work perfectly in his machine.

Having read various discussions in this forum I have tried the resets suggested to no avail. Similarly from the various discussions I have a feeling that the simplest, possibly cheapest and most convenient solution is to remove the harddrive - advice here would be appreciated - and get a new laptop, but I put this up in the hope that there may be some other solution (as does our son, who is fed up at us using his machine!)

Cheers