I decided to create a Ubuntu USB installer using the Universal USB Installer, selecting a Ubuntu 12.10 ISO. I selected my D: drive, my NON-windows7 carrying drive as install. After this I Re-booted my system and my PC began to Run the Ubuntu Boot-startscreen every time I power up the machine, giving errors like this: Root=Unknown

I used my girlfriend's laptop to create, on the exact same way, a real! USB Ubuntu installer.

Booting from that USB, picking the option Run Ubuntu from this USB I get the following error:
http://postimage.org/image/63qkv98c1/

Let's try installing it from that USB to a Hard-Disk: http://postimage.org/image/usqbwymfx/

As I said: I do not have the Option to pick my Boot-section, at this very moment I can only access to the Ubuntu installation and nothing else.

I've read about 90% of other Questions that could've been related, but I could not find a solution.

BTW I'm running a Acer Aspire 2Quadcore 4gb DDR 2 Ati Radeon HD, 64bit and I've set my Bios OS-usage from Windows to "Others"