I just brought a new LCD Monitor "Acer AL1916W", After connect to my computer, the monitor color showed weird , especially, red color was gone, only yellow, black and blue were still there.

Connecting cable is correctly connected. My installed display card is
NVIDIA GFORCE 2MX / MX400
The former time, everything was OK when connected with CRT monitor

Please comment how to solve this problem.

Somkiat

Boot into safe mode and install the monitor driver if provided.

Ensure you have updated video drivers.

Check that your driver supports 1440x900. Check that you have 32 bit color depth.

Check for possible bent pin(s) on the VGA connector.

How much ram is on the MX400? 32 MB? 64 MB? If 32 it may not be enough to drive the monitor. Perhaps time for an upgrade. Video card prices are quite reasonable nowadays for 128MB, and even 256MB is becoming standard now.

Try the monitor on another computer (if available) or maybe bring to a friend's or relative's house.