display not working after startup

Ok so I´ve got a macbook pro that is out of warranty and just installed a new screen. The install itself went fine and everything seems fine at startup, I see the apple icon and everything looks great. But once snow leopard boots up the I am getting horizontal lines flickering everywhere and I cannot see anything on the screen.

I´ve seen similar posts about flickering lines, but nothing like this where they only show up after bootup. There must be a way to fix this... apple software update says my video driver is up to date. I tried messing with some basic settings on display settings, but no luck.

Can anyone help me with an explanation for this??

 

Thanks for the quick reply.

I guess it must be a defective screen, because I reinstalled the old (cracked) screen and it still works fine.

I just dont understand how it could be a defective display if the problem only starts after osx boots. As I mentioned, the startup apple screen displays perfectly. Plus it is an new replacement display.