I have an imedia as my standby pc, on beep is normal as is the bios screen. If it was the graphics card then there would also be a problem with the bios screen. Sounds more like it is not recognising the hdd and therefore not booting in the os. First check the hdd has not been inadvently been changed to another drive to boot in the os. Also it would be worth ch3ecking the hdd in another pc to see if it is working or if it has failed.
I had a drive that failed and the symptoms are very similar. Hope you have all your files backed up!