My tv won't display picture after startup using VGA

I have a slightly older Maxent 42" plasma which I am trying to use as my monitor. I have gotten it to work with previous computers but this one is giving me trouble. It will display the bootup screens no problem but once windows goes to display the desktop then I lose signal and the screen goes blue. If I am quick enough I can pull out my small monitor vga and plug in the one to the TV and it will display for a second, then shuts it off for some reason. I took a video of the bootup, you can see it boots until the starting windows screen, then loses the signal, but when I hook it to my little LCD it works fine. Please help. Thanks.

http://www.youtube.com/watch?v=0exQCx8KR3g

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EDIT: no wait a minute. It seems like the HD 6530D is an integrated GPU, and looking at specs seems like it's limited to up to 2560x1600 resolution, which would be a 30-ish'' screen, but that is a 42'' one.
No wonder it freaks out.
Try to alter TV options (if possible) to have a screen resolution within the gpu's limits, or buy a discrete GPU card, even 50-60$ ones will do.
You can try what I said below, but I think it won't work.
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Try booting the PC with a normal screen, then connect the TV, go in Screen Resolution (right-click on an empty are of your desktop) then select Detect and see if the TV gets detected as a second screen, and works fine as secondary monitor.
Then switch to it as primary screen, power off, disconnect the normal screen, power up again.
I know, you probably need a DVI-to-VGA adapter and another VGA cable or a DVI cable.

Also try looking into the TV's own options and manual to see if there is something that can be done on its side as well.