Shuttle XPC SS30G2 instability?

Hello,

I built up this configuration by myself:
- Shuttle SS30G2, BIOS updated to the latest version of December 2006, newest drivers
- Power Supply upgraded to Shuttle PC50 300W Supersilent
- Intel Pentium 4 D945 Dual Core 3,4 GHz
- 2x 1GB DDR2-800 G.Skill CL4
- Asus EN7600GS Silent passive, PCI-X16, 512MB DDR2, newest drivers
- 500 GB HDD Samsung SpinPoint T166 HD501LJ
- DVDRW NEC Optiarc AD-7173A silver
- Fiberline Gigabit Ethernet Adapter as PCI-card
- MS Windows XP Professional SP2

I have several problems:
- in windows I use a program that tries to build up a serial connection but during "finding bitrate" it hangs (I tested the port with a loopback adapter under DOS with PC-Check and that was ok)
- sometimes windows hangs when I start XPC tools
- the system reboots when checking a cd-key of a application against an inserted cd-rom
- once the system even hung in the boot process of the BIOS
- the system hangs when I start Acronis True Image via boot-cd

Beside these problems the normal operation is very fast.

The temperature is about 40-50 degrees celsius.

The only mistake I found out in the configuration is that the board only supports up to 667 MHz memory chips. But shouldn't it work that the 800 MHz memory chips decrease the frequency to 667?

Do you know another reason or is it the memory frequency? But what should that have to do with the serial communication or cd-key checking?


Does anyone have an idea?

Thanks,
Stephan