Vista - NoBoot after STR or turn off. SATA

Hi all,

I have one seriously annoying problem going on with installation of Vista 64 Home premium OEM (czech). Problem is occuring on system running M3N78-VM motherboard with 8200 integrated GPU, Athlon II 240 CPU, 4GB of RAM (128 MB allocated for integrated GPU), one Samsung 250GB F1 SATA hard drive and one Samsung SATA DVD writter.

so problem follows :
First installations unsuccesful - problems with IGP running at all and sudden freezes at or after instalation, all in all I was able to get to desktop for one time. So Problem was in BIOS as I found - upgrade solved graphics flickering and freezes.

After BIOS upgrade all seemed fine, however, one very bad behavior came up:
PC installed all fine, HDD in SATA connector 1, DVD in connecor 2. Drivers installed also fine, all up and running. first thing that started to bother me was function of integrated NIC, but it works in the end.
Getting to the burried dog - After day of work, PC was put in Vista STR state. Next day followed by BSOD while attempting to turn the PC on. As I experienced one problem similar to this on my older ASUS MoBo, I tried to swap HDD connector to the 3rd (simply said, swapping HDD connector in other one) and the PC went up fine. Next day the same problem - solution was simple as it was the last - plugged the connector in the place where it was in the beginning, and voila, PC ran up fine again.
So I wanna ask You people, if somebody is experiencing similar problem and would know way to fix it so I wont have to open case every day to SATA swap?

PS: I tried to simulate the conditions of BSOD by turning the PC to the STR and waking up - no probs, second condition - shut down and turning off PSU - also worked (however one time I managed to get the BSOD) - problem occurs overnight, so maybe motherboard time is also included in the problem?

Looking forward to replies and hope You guys are familiar with way to fix it, the problem is utmost painful cause the PC is of one customer.