Dear Clueless in SD: (sorry, I couldn't resist)
When whs said BIOS, he was talking about the system's BIOS, not the graphics adapter's BIOS. Yes, it's confusing. When your system is booting up, from power on or restart, there should be an option to press F2 or Del or some key (it varies) to take you into the system BIOS which may also be called "Setup Utility". This is the BIOS we want you to check.
Also, when the system BIOS or Setup Utility or whatever is coming up, it runs in a very standard low resolution that any monitor on the planet should be able to handle. Once you are in these menus, we hope you will find something such as "Onboard graphics" that is set to "Disabled" and you can just flick it on again. These setup utilities also vary widely, and the setting may not be obvious. Post back with whatever results you have and we will continue to assist.