I've got a Dell Precision M4600 laptop, running Fedora 17. Sometime after kernel 3.7.9-104, the external VGA output no longer works.
If I boot with 3.7.9-104,with my projector attached, it is recognized. If I boot with 3.8.4-102, external VGA devices are not recognized.
lspci:
01:00.0 VGA compatible controller: nVidia Corporation GF108 [Quadro 1000M] (rev a1)
(I've tried running the driver from nVidia, but that has screen rendering problems, with blocks of random data instead of my normal background pic)