Medion Laptop trouble...

My Medion MD5400 has really started acting up. Some times it woun't start up. Just comes up with a black screen stating "No operating system found". I found out a trick that works. Turn the laptop upside down and then shake it a little. Voilá! Then it starts up. Usually. There must be a bad connection somewhere. But where...?

Over time I have modified the original. I changed the harddrive from a 40 GB Hitachi 4200 RPM to a 60 GB Western Digital Scorpio, 5400 RPM. The Scorpio is much more quiet. And faster.

I put in extra ram. 2x 512 DDR Pc-2700 (200 pins) and last but not least I changed the CPU from a Pentium 4, 2.53 GHz, 553 FSB desktop to a mobile Pentium 4, 2.0 GHz.

The desktop CPU got way too hot, and as a result the speedstepping feature caused it to go as low as 300 MHz. It's a known problem for this laptop.

I had to put in a little copper plate (1 mm) between the cpu and the heatsink to make sure that they touch. The temp. dropped about 10 degrees Celcius doing this trick. Also the mobile doesn't use the speedstep trick, so it always runs full speed. Or at least 1.6 GHz.

And thats another odd thing. It is a 2.0 GHz CPU, and detected like that i BIOS (or at the boot screen) but in Windows XP it runs at 1.6 GHz. I can't figure out why.