I had exactly the same problem on my mom's T23.
The computer worked fine for a couple of hours at a time, but after that it always froze and only the CPU fan continued going on and off. Also the display had a darker bar at the top edge of the screen. Those were the only life signs at that point.
I might also add that
the problem was worse while running on battery. It only worked for about 15 minutes and then froze every time. It always started working again after a few hours, though.
I opened up the computer yesterday in hope of finding a loose "magnet thingy". I disappointingly found that all three were attached, but
when I applied some force, two of them popped right off. The one on the top of the MB and the one in the pictures above.
The contact surface of the "legs" of the magnets had a worn coppery color. I polished them and soldered the two magnets back on...
(dramatic pause)
...and what do you know, that seems to have solved the problem! I was at least able to run the computer normally with the battery for over two hours, which is something I couldn't even have dreamt of before.
So bottom line, even if the magnet things seem to be attached, I'd still remove them by applying some force after going through the trouble of opening up the computer. It won't do any harm and I suppose they'll fail on every T23 sooner or later.
I'll do some more testing, but it looks very good so far. Many thanks to all of you guys!
Btw, I registered just to post this.
