All I can say that this is my conclusion and no, I can't remember any error codes. The resets appeard at the beginnig rare and in days more frequent until no start posible (and this with any changes before or after the first reset, except BIOS and Intel AHCI driver with the newest version). The effect was, that in a HD read request the LED remaind ON and after 15 seconds (I suppose of "innactivity") followed a "blue screen" and reset and this in different situations. In this time I didn't change any drivers or software installation (my PC was perfect). After the fresh install with the same software on it ,all works perfect and no more troubles (tested in very hard situations). I don't want to say that the AHCI drivers caused the "death" of my PC, but XP makes the things different and better in a fresh installation as in a simple driver upgrade. ASUS P5K Premium/Wifi IC2 Q6600 2400 2GB DDR2 800MHZ ASUS N8800 ULTRA WD5000AAKS SATA ASUS DRW 1814BLT SATA CORSAIR CMPSU-520HX