rather than the logic board.
The flashing question mark, the missing disk under the startup manager and the rebooting several times before success, all point toward a drive problem.
Get the data backed up ASAP and consider your options.
1. Clean install of the OS
2. Archive and Install of the OS
3. Replace the drive
I would go with #2 first but I would also contact Apple, under the AppleCard, to start the ball rollling on a replacement drive.
Let us know how you get on
After my MacBook Pro 2.5's logic board failed( and was replaced under AppleCare) after owning my MBP for just 17 months, activity monitor often shows asl ( system log file) manager at about 100% CPU. Fans spin at 5000rpm.
Never had this issue before the logic board replacement.
Also, Safari 4.04 frequently crashes; never had this issue either before, either.
Occasionally, after restarting my MBP, the Apple doesn't appear on my screen but instead I get image of a folder alternating with a question mark.
When trying to use installation disk to start up, under 'select the system you want to use to start up', Mac OS 10.5.8( the OS that's on my hard drive, will not show at all...it's missing. After restarting several more times with installation disk OS 10.5.8 eventually appears as a selection.
Why would these issues appear only after the LB was replaced.
I suspect that the replacement logic board or its installation is not 100%. Something's not quite right there.