I installed OS X and it would go to the apple boot screen but it flashed to a blue screen then the screen went blank. This was after I changed from AHCI to Compatibility in BIOS settings. When it was set to AHCI it would only go to the boot screen and then a little picture similar to a no smoking sign would appear in the middle of the apple logo. Could somebody please help? I'm using a Gateway P-6825. Processor Intel® Pentium® Core™ 2 Duo processor T5250
1.5 GHz | 2 MB L2 cache | 667 MHz FSB Chipset Intel® GM965 Display panel 17-inch Ultrabright™ WXGA+ TFT (1440 × 900) Memory 2048 MB 667 MHz DDR2 SDRAM (2 × 1024)
Operates at 667 MHz|Video controller Intel® Graphics Media Accelerator X3100
384 MB of Dynamic Video Memory

Keep the AHCI switched to Compatibility and try installing without graphics drivers, this should allow to to get to the desktop in VESA mode.

---

 Mac OS X 10.6.4 Retail || Intel Core2 Duo E8200 2.66GHz || Gigabyte G31M-ES2L || GeForce 6600 GT 128MB || Realtek ALC883 Audio || Realtek RTL8169 LAN || Samsung SpinPoint F1 1TB HD || Sony Dual Layer IDE DVD RW DW-D22A || Apple Aluminium Keyboard || Mighty Mouse

 MacBook Pro || 2.4Ghz Core 2 Duo || 200Gb HD || 2Gb Ram || NVIDIA GeForce 8600M GT

 iPhone 4 || 16Gb

I did a complete reinstall minus the graphics drivers and booted up in Compatibility and it is still doing the same thing. Goes to blue screen then straight to blank.