Both graphics cards status have 'no display connected'.

I always have problem watching a video clip on my Macbookpro Unibody Mid2010

Freezing, or flashing screen

Problems with autocad, mouse freezes every 2secs

I wondering if my graphic card has a problem... I read 'how to determine which graphic card is in use from http://support.apple.com/kb/HT4152

Then I notice none of my graphic card is in use......

Hardware Overview:

Model Name: MacBook Pro

Model Identifier: MacBookPro6,2

Processor Name: Intel Core i7

Processor Speed: 2.66 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache (per core): 256 KB

L3 Cache: 4 MB

Memory: 4 GB

Processor Interconnect Speed: 4.8 GT/s

Boot ROM Version: MBP61.0057.B0C

SMC Version (system): 1.58f15

Serial Number (system): W80***DTAGW

Hardware UUID: 0C3DD217-6B8C-51CE-9D0C-4D865EE4E872

Sudden Motion Sensor:

State: Enabled

Intel HD Graphics:

Chipset Model: Intel HD Graphics

Type: GPU

Bus: Built-In

VRAM (Total): 288 MB

Vendor: Intel (0x8086)

Device ID: 0x0046

Revision ID: 0x0012

gMux Version: 1.9.21

Displays:

Display Connector:

Status: No Display Connected

NVIDIA GeForce GT 330M:

Chipset Model: NVIDIA GeForce GT 330M

Type: GPU

Bus: PCIe

PCIe Lane Width: x16

VRAM (Total): 512 MB

Vendor: NVIDIA (0x10de)

Device ID: 0x0a29

Revision ID: 0x00a2

ROM Revision: 3560

gMux Version: 1.9.21

Displays:

Color LCD:

Resolution: 1440 x 900

Pixel Depth: 32-Bit Color (ARGB8888)

Main Display: Yes

Mirror: Off

Online: Yes

Built-In: Yes

Display Connector:

Status: No Display Connected