Restarted my iMac and now it's stuck on the blue screen

Question

I have not had a problem with the actual computer since I received it a year ago.
This is what I did on my computer today:
I downloaded Google Chrome, for the sites that don't really work as well with Safari and then later on, I changed a couple of the Folder Sharing permission for a few picture folders and a couple of document folders so "Everyone" does not have access to them, only me. I went into my System Preferences > Accounts to see who was under "Staff" and any other computer I tried to connect to. I tried to unlock the Accounts section and my System Preferences kept freezing, so I had to force quit it.
Every time I had a freezing issue with my PC, I always restarted it, so that's what I did, I restarted my iMac. Now, it only shows a blue screen. It goes through the gray screen with the apple logo, and then the blue screen. I see my cursor to my Magic Mouse for a few seconds and then it vanishes. Now all I have is a blue screen and it's been on a blue screen, this time, for about 15 minutes.
I tried to hold down the power button, mainly out of panic, and I also unplugged everything and then tried to turn it back on and that hasn't worked.
Please help. : (

Answer 1

Sounds like you changed some of the file and share permissions
incorrectly and then complicated things further by hoping a restart
in the middle of this mistaken direction could cure it somehow.
Sometimes that works; but some parts of the system are not to be
messed with, since some items have to be where they are to work.
And some kinds of keyboard/mouse functions on boot are reluctant
to perform with a bluetooth or wireless mouse & keyboard; so a USB
wired keyboard is very handy to own & have on hand. I have spares.
(You may have to try and see if a power management reset can help,
if the problem has compounded by now into more than the first issue;
a System Management Controller reset. (Don't recall how, but this
will vary with the model and build year of the computer.) And it may
not help resolve the issue; booting from the installer disc may...)
Some command keys require early power in the keyboard; sometimes,
a wireless keyboard or mouse won't be seen by the computer at a
critical moment in early boot stages; so a procedure may not occur.
Keyboard commands and shortcuts on boot are important to use &
know in the case of troubleshooting and maintenance.
Can you start the computer from the OS X install disc that came
with the computer (or if you've upgrade the OS to a later than
originally shipped version, use the latest retail disc) by holding
the C key down on boot, until you see a window with either a
choice to select a language or (maybe second window) a menu
in the top of the screen, where you see Installer (instead of Finder)
and check the top menu bar by clicking to read the drop-down
menus, looking for Disk Utility.
When you find Disk Utility, as indicated from the booted Installer disc
(disc #1 of a restore install set) select the name of your computer drive
which probably is Macintosh HD in the Disk Utility left side-bar, and then
click on 'repair disk.' When that is done, note if there is a message in
the little screen inside the utility, what it said; then choose to run the item
named 'repair disk permissions' and then restart the computer normally.
This would include selecting the computer's hard disk drive from an
option in the Installer's menu bar after quitting Disk Utility; to choose
from a startup manager, the Macintosh HD as a boot volume, & restart.
You could try and see if the computer would re-start and with the Shift
key held down, through the boot process (from the hard disk drive OS)
and if it gets to a point of asking for your Admin password, enter it, &
continue until a desktop appears. If this works, use GO in the Finder
top menu bar and find Utilities folder, open it, and find Disk Utility, then
run 'repair disk permissions' on the volume Macintosh HD. + Restart.
This may not work, but if it sorta does, you could try and see if things
run OK. Another possible fix (without performing an Archive & Install
from the booted Install disc) may be to get the Combo update file for
the OS X version you have in the computer already, & reinstall it.
Be sure to repair disk permissions before and after this kind of action.
If you want other users of your computer to not access your files, be
sure to set up other user accounts with less than Admin privileges.
Then understand how security works in Mac OS X. Your user folder
content is not normally accessible by someone running that computer
from a different user account, if the computer is used correctly.
One of the better Mac browsers is Camino from Mozilla; FireFox is OK,
and for some users, Opera is fine enough. There are others; and I am
not so sure about Chrome at this point. No real need for me to use it.
In any event...
Good luck & happy computing!
{ edited 2x }