Does that mean that my video card is bad???
1.
Bad video card? I don't know... Could use some "help" here.
2.
Display Settings. I believe display settings are applied when the desktop is opened. Screen going "blank" at this stage may indicate the "current" settings are outside the range monitor can support. You should check the specs to see what the video card, monitor, and monitor cable support. And no, I don't know why unplugging and plugging recovers the display. (What - monitor power or data cable?)
If display remains stable after boot to "Enable VGA mode" let's walk the settings up bit by bit until it either "fails" again or is at an acceptable level. Or conversely, you could set them to the values you prefer, and if it fails again, walk them down to an acceptable level. (Do a "Normal" reboot to desktop to verify stability after each change.)
Enable VGA mode defaults to following display settings:
a. Screen Resolution: 640 by 480 pixels
b. Color Resolution (depth): 8-bits
c. Refresh Rate: 60 Hertz
Recommend you try following settings:
a. Screen Resolution: 800 by 600,
1024 by 768, 1152 by 864, 1280 by 1024
b. Color Resolution: 16-bits, 24-bits,
32-bits c. Refresh Rate: leave at
60 Hertz for LCD
LCDs have a "native" (or optimum) mode they support. That's probably where you want to run if video card and cable supports it.
3.
Reference(s):
a.
A Complete Guide to the Digital Video Interface