I have to reinstall OSX upon every restart

Question

I have the oddest problem.
Two weeks ago I restarted my computer and got stuck on the grey apple startup screen. At first I thought my HD was the issue. All of the data was accessable, and no signs of an issue (disk utility confirmed) Even knowing that I transferred all of the data over to a new drive and reinstalled OSX (not a clean install). All booted fine. It even booted upon every software update that was required. No issues while working from that point on, untill I needed to reboot. When this happened, I was faced with the forever grey apple startup screen again. I repeated the process, all booted fine as explained above, but this time I scanned for any viruses (not expecting any). Disk utility confirmed all was good with the new drive, and also with the old. All runs perfectly while on. I am confident that this is not a HD issue (mechanical). Moments ago I had to reboot with fingers crossed. Machine has been running for days with no issue. I'm back to square one. Something seems to be messing with what is required to startup on the drive. I have lost no data during these events. Here's my issue. I know I could do a clean install, but I have so many applications, and audio plugins, that have been authorized over the years - tracking down 3 year old serial numbers, and reinstalling items I might have even forget I was using would be a task I can't bare to think of. Any help would be wonderul. Even if I had to do a clean install, would there be a way to save that data and transfer it over without having to go through the relicencing of all of those apps, etc.? Yikes, what is going on? Is this a "genuis bar" canadate?
Thanks in advance for your wisdom.
L
Mac Pro 12 Core, Mac OSX 10.6.8

Answer 1

When you reinstall just OS X, it overwrites itself and those bundled Apple programs with a new (but older) copy then you Software update to get current on 10.6.8
Some third party software you install installs a at boot kernel extension file that gets loaded when OS X loads, if there is a problem with that software it causes the gray screen and spinning wheel thing when you boot up.
When you install OS X over itself it removes these kernel extension files as they don't belong.
So I suspect it's software you installed AFTER resinstalling OS X when they didn't work is what is causing the problem. (likely the anti-virus, unless it's ClamXav)
Also it might be software installed when you log into the machine it's set to automatically launch, but that usually occurs after you log in and gives a Kernel Panic, (black screen and you need to restart message)
So what you can do is hold the Shift Key down upon boot, this will enter Safe Mode and you can uninstall and/or update those programs. Or reinstall OS X again to clear them out, then get online and check for updates to all your third party software.
..Step by Step to fix your Mac
Once you get your machine fixed, you should clone that boot drive automatically to another internal drive with Carbon Copy Cloner
That way you can hold the option key down and boot from the clone.
Most commonly used backup methods
Also you should be considering Deep Freeze at this time, as Apple is likley about to drop support for 10.6
Turn off Java in all your browsers and via the Java Preferences app, it's a major security risk (so is Flash, so use it off most of the time)
Use Firefox or (yucky spyware Chrome) as it's getting security updates and there is no Safari 6 for 10.6 (only not secure Safari 5.7.1)