a. An Apple TIL file describes what is probably going on if, after installing 7.6 and restarting, you get a blinking question mark:
"This behavior occurs only with hard drives that were formatted with an older version of Apple HD SC Setup (7.1.2 or older). Although there is nothing physically wrong with the hard drive, and no information has been lost, there is currently no utility that would allow access to the data. A drive recovery service may be able to recover the information on the drive. To reclaim the use of the affected hard drive, reinitialize it with Apple HD SC Setup 7.3.5. Apple is working on resolving this issue."
Whew! This is serious!! You would think that this would have merited a mention in Apple's Info Alley. At least Apple posted it to their Technical Support Online page. The TIL implies that if you currently have a 7.1.2 formatted drive, you could avoid this problem by updating to a newer version prior to installing Mac OS 7.6. Unfortunately, the TIL file gives no indication of what exactly causes this problem to happen. (Thanks, Jonathan Hue for spotting this link!)
Update: Lance Taylor-Warren reported success in recovering from this problem by updating the disk's driver with the one from FWB's Hard Disk ToolKit. On the other hand, Charles Minckler reports having a similar blinking question mark problem using Silverlining v. 5.7; suggesting that the problem may extend beyond Apple HD SC Setup.
b. With some similarity to the Apple report, Chris Heatherly (from Power Computing) last wrote us to suggest that a warm reboot blinking question startup problem that some users saw after updating to Mac OS 7.6 might be due to updating Drive Setup to 1.2.2 on IDE drives (although some other readers suggested this might be restricted just to Power Computing clones). Chris now writes with new information:
"The issue only happens with internal IDE drives when an external SCSI hard drive is connected.
While there appears to be a connection with Drive Setup 1.2(.2?) and reinitializing with Drive Setup 1.1 does resolve the issue for many customers, it has not in all cases.
Based on the responses I have seen, there may be a connection with the Energy Saver spin down option."
c. Here's a related problem: When running the Mac OS 7.6 Installer, do you get a message that says: "This media is not partitioned, unable to update the driver."? If so, another Apple TIL file states: "This happens only when the drive has been formatted with the Internal HD Format program included on 580 Series, 630 Series, 5200 Series, and 6200 series computers. The solution is to back up the hard drive and reinitialize (low level format) it with Drive Setup 1.2.2."
d. Finally, don't forget that Mac OS 7.6 will not install on Power Macintosh 4400, 5500, 6500, 7300, 8600, or 9600 computers. You folks have to wait for 7.6.1.