Booting into OS X x64 using GRUB causes BIOS to reset

[EllisCEC]

Hi,

Since installing Ubuntu, I stuck with the GRUB bootloader it comes with to control my triple boot. At startup, it presents two options for Mac OS X. 32-bit and 64-bit. If I chose to boot into 64-bit, the BIOS settings reset themselves upon restart, and startup fails with a 'CMOS checksum error'. I can resolve the problem by booting from 'last good boot' settings. No damage is done, but it's highly annoying. Does anyone have any ideas as to what is causing this?

 

Notes

This doesn't happen when booting into 32-bit OS X.

Happens whether hard or soft restarting.

Happens whether restarting or shutdown>>power back on.

Booting is now 'verbose', it doesn't show the apple logo any more.

 

System Specs

• [Operating Systems] Ubuntu 11.04, Mac OS X 10.6.8, Windows 7
  
  
• [Motherboard] Gigabyte EP45-UD3P
  
  
• [Processor] Core 2 Quad Q6600 @ 2.4Ghz
  
  
• [Memory] 2x2GB Gskills FD-8500-CL5D
  
  
• [Graphics Card] Sapphire Radeon HD 5770
  
  
• [Discs] 120GB OCZ Vertex II SSD, 2x500GB WD HDDs, 2x2TB WD HDDs, 2x2TB and 1x1TB external discs
  
  

Regards

Ellis