My iMac crashed while BA was starting up and when it restarted the display was initially stuck in 640x480 (rather than the native 1920x1200) mode. After some digging around it looks like this was because the primary display adapter was being mirrored to a second 'virtual' adapter which shows up as "VGA Display" in the display preferences. By un-mirroring the displays I can get my normal display back however this leaves me with a second 'virtual' adapter which I can't get rid of and causes problems as the OS tries to span windows across the screens and switch displays if you move the cursor too close to one of the edges. I can't find any way of getting rid of this.
I assume that BA was in the process of setting up the displays when this happened and something is now mis-configured. ANy ideas on how to fix this?
Extract from system_profiler below (you can see the fake screen in the Displays section)
Hardware:
Hardware Overview:
Model Name: iMac
Model Identifier: iMac6,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.16 GHz
Number of Processors: 1
Total Number of Cores: 2
L2 Cache: 4 MB
Memory: 2 GB
Bus Speed: 667 MHz
Boot ROM Version: IM61.0093.B07
SMC Version (system): 1.10f2
Serial Number (system): W8640011VGP
Hardware UUID: 00000000-0000-1000-8000-0016CB9F9001
Graphics/Displays:
NVIDIA GeForce 7600 GT:
Chipset Model: NVIDIA GeForce 7600 GT
Type: GPU
Bus: PCIe
PCIe Lane Width: x16
VRAM (Total): 256 MB
Vendor: NVIDIA (0x10de)
Device ID: 0x0391
Revision ID: 0x00a1
ROM Revision: 3021
Displays:
iMac:
Resolution: 1920 x 1200
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes
Built-In: Yes
VGA Display:
Resolution: 800 x 600 @ 60 Hz
Pixel Depth: 32-Bit Color (ARGB8888)
Mirror: Off
Online: Yes
Rotation: Supported
so I suspect that BA was just an innocent bystander.