Z77X-UP5 TH installation issue

[Litestream]

I just assembled a new PC with the following components:

Gigabyte Z77X-UP5TH Motherboard
Intel Core i7 3770K Processor
Corsair 32GB XMS3 RAM
Corsair H60 Cooler
Corsair 650W Power Supply
240GB Corsair GT SSD
2TB Western Digital Black Hard Drive

I tried loading my Windows 7 DVD, got into the BIOS to set the first boot device as the DVD player. It starts loading the Windows files then the screen cycles White, Black, Horizontally Striped Red-Green-Blue-White, Grey

Any ideas what is happening please?

I haven't installed a standalone graphics card

[Litestream]

I solved this issue by switching out the VGA cable for an HDMI cable. No idea why the VGA wouldn't work.

[Litestream]

I now have a new issue with my new PC:

I can connect to the local network and can see the other computers on the network, but I cannot connect to the internet.

If I reinstall the LAN drivers, I can connect to the Internet but when I reboot the next time, I can only see the LAN computers again.

Anyone able to assist please?