Q: A grey progress bar will appear and will load for a little bit and will shut off, what do I do?

OS X v10.6- Gray progress bar appears under Apple logo during startup

Startup - Gray, Blue or White screen at boot, w/spinner/progress bar

Startup - Gray Screen

Startup Issues - Resolve

Startup Issues - Resolve (2)

Same things been happening to me too. I can't even start in safe mode!

Boot off the Snow Leopard DVD. Run Disk Utility Verify/Repair and Repair Permissions until you get no errors. Then re-install the OS.

FOUND THE SOLOUTION TO EVERYONES PROBLEM !!!!

1. GO TO SYSTEM PREFERENCES

2.SECURITY AND PRIVACY

3. FILEVAULT

MAKE SURE ITS OFF AND THE GREY LOADING SCREEN IS GONE IT WILL TAKE A FEW HOURS BEFORE THE DISC BECOMES UN-DE-CRYPTED (IF THATS EVEN A WORD) ONCE ITS DONE YOU SHOULD BE GOOD TO GO !!!!

Thanks very much.  Was exactly what I was looking for.

If the computer doesn't start up how am I to go to system prefs? 

Obviously, turning off FileVault is not going to work for the original poster since their computer shuts down during startup. I guess reading comprehension is no longer included in SAT tests? Also, typing in all caps is obnoxious.

I'm having the exact same issue, where you able to find a way around it?

I was able to find a way around

This seems to work. The machine is running and booted up so far. This case is not FileVault.

Do you know what the corruption is?

Thanks for your post.

Honestly, I have no idea. But this has only acted as a temporary fix for me. I have to do it every time I restart my system

Same thing was happening to me. I went to visit the Genius Bar where they started my MacBook from the network and ran disk repair. That didi not completed successfully, so I ended up needing to replace the internal drive and restore the operating system from a disk image. Hope this helps.

Thanks, it does.

I Appreciate the posts being updated.

It sounds like you may have experienced a hardware failure. But I am not so sure that is what these other folks are dealing with.

As glenndon 1995 posted this was a temporary fix that needs to be done from time to time.

This sounds to me like an operating system problem. I checked for third party application problems but found none and the issue returned.

I am going to keep looking and will post a solution if or when I find it.

Thanks for all of your input!