flashing with blue screen

I have finished my installation(Zephyroth 10.5.2.Rev.2) and successfully boot into Leopard.

When installing it, I have chosen "NVidia kexts 10.5.2" and "NVinject 256MB"

However, after I logged into Leopard, the screen keep flashing with a light blue screen just after few seconds of normal use(no video, no games, just normal use).

It is NOT the refreshing thing on CRT display, I use LCD display. It just flashes like <b>"normal diplay" -> "whole screen blue" -> "normal display"</b>. Sometimes with whole black screen like no display signal is inputed.

PS: I can change display resolution and refreshing rate. Now I get 1280*1024 @ 60HZ. Decrease the resolution doesn't solve this problem.
In System Profile it says that QE/CI is supported. I don't know whether this info is helpful to analyze the problem.

Anyone can tell what is wrong? The display driver or what else?...any suggestion?

My specs:

AMD Athlon 64 3000+
Biostar TForce550SE with nForce 550 chipset
Kingston DDR 512*2
Seagate 80G SATA
Galaxy GeForce 7300GT
Samsung SyncMaster 740N+ LCD display