I don't have a bootcamp partition, and my hard drive is not RAID. Why do I still get this message and what can I do to resolve it? I used PGP whole disk encryption previously, but have turned that off for now.

Thanks for the quick response! Not exactly interested in doing a full backup/erase/re-install....but, if I did, I still have several questions:

would I use Time Machine for the backup?

and then what OS would I re-install, my Snow Leopard first and then restore my backup (and why would I need to do anything with setup assistant if I am doing a full restpore?)

and then would I upgrade to Mountain Lion?

Is that the right sequence?

I am really curious to learn why this is doing this. Why am I getting this error? I am looking for both an explanation and a solution.

Thanks for any help !

How will erasing the hard-drive allow Mountain Lion to install this restore partition and let me get past this error?

Why do I get the error in the first place.

As far as I can tell, I have a fairly standard Snow Leopard installation. Has everyone who upgraded from Snow Leopard gone through this?

In case it helps, here are specs on the system:

OS X version 10.6.8

MacBook Pro

2.8GHz Intel Core 2 Duo

4 GB 1067 MHz DDR3

Interesting, when I look at the serial-ATA hardware devices in System Profiler, I see my Hitachi drive with the following information under "Volumes":

Volumes:

Capacity: 209.7 MB (209,715,200 bytes)

Writable: Yes

BSD Name: disk0s1

Macintosh HD:

Capacity: 499.76 GB (499,763,888,128 bytes)

Available: 271.91 GB (271,908,753,408 bytes)

Writable: Yes

File System: Journaled HFS+

BSD Name: disk0s2

Mount Point: /

Boot OSX:

Capacity: 134.2 MB (134,217,728 bytes)

Writable: Yes

BSD Name: disk0s3

What are those BSD names disk0s1 and disk0s3 ????

Could they be part of the problem?

Thanks for any help.

Yes, and thanks for the advice of backing up my system, installing Mountain Lion and then migrating my data and applications. I understand that is a solution.

I don't have a backup solution other than Time Machine and it sounds like your advice involves a third party backup solution ($39.95), unless someone confirms I can use Time Machine for this.

What I don't understand is - this is a regular Macbook Pro trying to go through a regular upgrade. Why can it not perform the upgrade normally? Is there some situation Apple did not plan for that requires me to wipe my hard drive for this upgrade? Or have I done something to my hard drive that I need to undo? The only thing I've done that comes close to messing with the hard drive is using PGP Whole-Disk Encryption - which I have since undone.

Can anyone answer this question of why this is happening?

and can I get confirmation that I can use Time Machine as a source for Migration Assistant after wiping my system and installing Mountain Lion?

Thanks

After a quick search it does seem I can use Migration(Setup) Assistant with a clean install of Mountain Lion and my most recent Time Machine backup.

Now - to on to find out how to get a clean install of Mountain Lion (purchased upgrade in the store).

Ended up creating a bootable Mountain Lion disk. Clearing PRAM.

Then booting to that USB drive, erasing my hard drive and installing lion.

Then used setup assistant to copy everything from my Time Machine backup.

Took about 4 or 5 hours once I took that approach.

Thanks for the help and suggestions.