Actually, some newer laptops have their internal panels wired up as DisplayPort instead of LVDS these days. This appears to be one of them:
(--) Aug 03 20:53:54 NVIDIA(0): Connected display device(s) on NVS 3100M at PCI:1:0:0:
(--) Aug 03 20:53:54 NVIDIA(0): LGD (DFP-3)
(--) Aug 03 20:53:54 NVIDIA(0): LGD (DFP-3): 480.0 MHz maximum pixel clock
(--) Aug 03 20:53:54 NVIDIA(0): LGD (DFP-3): Internal DisplayPort
The DisplayPort warning message that appears in the X log is probably not related to the problem here. I've heard reports of Ubuntu Lucid machines not being able to start gdm properly every time, but I haven't been able to reproduce this failure myself:
It seems like some kind of timing issue that Ubuntu's startup process can trigger sometimes, but not always.