Installed mountain lion, Computer won't restart. Help!

Here's how mine went down:

1. Downloaded ML directly over wi-fi. Download and installation were completed, restart yielded the never-ending "spinning wheel of death".

2. Could not enter "safe" mode, but was able to enter "repair" mode. Used disk utility to verify permissions, which was successful.

3. Re-downloaded and re-installed ML, same result as before, spinning wheel ad infinitum.

4. Next Day, off to Genius Bar. Hardware scan was completed by tech, no problems found. It was suggested that with so many applications on my HD, a "clean" install from a freshly wiped HD was desirable. As I had backed up to Time Machine (external drive) immediately prior to my first attempted install this was okay with me.

5. Tech erased my HD and successfully installed ML at the Apple Store, but I went home to upload my apps and documents from my Time Machine backup.

6. Time Machine upload was successfully completed and all appeared to be running smoothly. Going through the set-up process I initiated my iCloud feature. This COMPLETELY SCREWED my .mac mail. After initiating iCloud my mail "Subject" and "From" lines no longer synced up with the actual email content that they were associated with. For example, my first message was From: Apple Store, Subject: Your Genious Bar Appointment, yet the actual body of the message was a totally different email from my Accountant!!! This was true for my .mac mail, but my other non-.mac mail accounts appeared to be unaffected. Go figure. Anyway, I figured I would pop back to the AS to have them "sort it out". Computer (Macbook Pro 17 BTW) Off, into bag.

7. Arrival Two at AS and I was lucky enough to get the same Genious at the Bar. Computer Out, Power On... You guessed it: SPINNING WHEEL OF DEATH!

8. Computer signed in for full diagnostic. No word back yet. I was told it could be a "bad HD". Seems awfully coincidental that I had NEVER had a problem with this computer before this download of ML, and I specifically waited for ML to avoid the horrible problems that I had read about with Lion. What's more is that my mail is now screwed up on all my other computers now as well, I suppose because Operation iCloud has taken over the entire mail system. Hoping that the mail from my original back-up will be salvagable, otherwise I'm pretty much screwed.

All in all I would say Mountain Lion is a massive failure. With 600+ Billion in market share you would think that these types of issues would be sorted out BEFORE a new OS is released. However, maybe I'm wrong and the issue really is as simple as a "bad HD". Not holding my breath. At least I backed up my files first. Good luck to you all!

Totally worked. Thx. Hope you've gotten big money from Apple but doubt it.