Hello nic, i have an ASUS K55V with the same issue.
So, i recently formated my PC and after i formated HDMI haven't worked anymore.
My PC detects the TV (37LG3000) and at first the TV said Invalid Format. So i've plugged the HDMI into another laptop that's also using an intel card (Not an HD4000 tho, an older model) and it worked (as that laptop always did) and when i went to the intel options i saw the PC was sending a 59 hz signal so i've plugged again back on my ASUS K55V and noticed i was trying to send a 23 hz signal, after testing i noticed that from 23 to 25 hz i'd get an invalid format error on TV but from 29hz and above i'd get No Signal error on TV. In both cases my PC detects TV and is using Clone Mode.
Hope this helps you detect the problem....